US3866530A

US3866530A - Apparatus for fabricating wood structures

Info

Publication number: US3866530A
Application number: US320900A
Authority: US
Inventors: Walter G Moehlenpah
Original assignee: Moehlenpah Walter George
Current assignee: Gang Nail Systems Inc; Mitek Holdings Inc
Priority date: 1973-01-04
Filing date: 1973-01-04
Publication date: 1975-02-18
Anticipated expiration: 1992-02-18
Also published as: CA1017546A; GB1407571A

Abstract

Apparatus for fabricating wood trusses of the type having lower chord members, upper chord members and web members extending from the lower chord members to the upper chord members. The apparatus comprises two presses each having an upper and a lower platen which are relatively movable toward and away from one another for driving nailing plates into two or more of the wood members of a truss from above and below, and means for supporting the wood members which are to be joined together by the nailing plates, the supporting means including a plurality of supports and means cantilevered relative to each support for holding wood members with clearance therebelow. One of the presses is mounted on a carriage adjacent the upper chord and the other press is mounted on a carriage adjacent the lower chord for movement of each press along its respective chord into an operating position at a first support for driving nailing plates into the wood members, and for movement in a generally lateral direction with respect to the press sidewise out of its operating position at the first support and into its operating position at a next successive support along its respective chord. Each press carriage is movable along its respective chord independently of the other, and has means for controlling movement thereof including means movable therewith for sensing the approach of its press to its operating position at a support in advance of its arrival at its operating position thereby to initiate deceleration of the carriage and for sensing the arrival of the press at its operating position at the last-said support so as to stop movement of the press carriage with its press at its operating position for driving nailing plates into the wood members.

Description

United States Patent [191 Moehlenpah Feb. 18, 1975 1 APPARATUS FOR FABRICATING WOOD STRUCTURES [76] lnventor: Walter G. Moehlenpah, 9906 Old Warson Rd., Ladue, Mo. 63124 [22] Filed: Jan. 4, 1973 [21] Appl. No.: 320,900

Moehlenpah et t l00/DlG. 13 Jureit l00/DlG. 13

Primary Examiner-Billy J. Wilhite Attorney, Agent, or Firml(oenig, Senniger, Powers and Leavitt ABSTRACT Apparatus for fabricating wood trusses of the type having lower chord members, upper chord members and web members extending from the lower chord members to the upper chord members. The apparatus comprises two presses each having an upper and a lower platen which are relatively movable toward and away from one another for driving nailing plates into two or more of the wood members of a truss from above and below, and means for supporting the wood members which are to be joined together by the nailing plates, the supporting means including a plurality of supports and means cantilevered relative to each support for holding wood members with clearance therebelow. One of the presses is mounted on a carriage adjacent the upper chord and the other press is mounted on a carriage adjacent the lower chord for movement of each press along its respective chord into an operating position at a first support for driving nailing plates into the wood members, and for movement in a generally lateral direction with respect to the press sidewise out of its operating position at the first support and into its operating position at a next successive support along its respective chord, Each press carriage is movable along its respective chord independently of the other, and has means for controlling movcment thereof including means movable therewith for sensing the approach of its press to its operating position at a support in advance of its arrival at its operating position thereby to initiate deceleration of the carriage and for sensing the arrival of the press at its operating position at the last-said support so as to stop movement of the press carriage with its press at its operating position for driving nailing plates into the wood members.

34 Claims, 13 Drawing Figures PATENIED FEB I 8i975 SHEEI 30F 9 m OE mgmgnnmsms 71.866530 saw u m 9 FEG.5

PATENIEDFEH I 81975 SHEET 5 OF 9 FIG.IO-

PATENTEDFEB I 81975 SHEET 8 OF 9 FlG.7

x I l FEGB Ufa,

PATEHTED FEB I 8 I975 sum 70F 9 mi LY APPARATUS FOR FABRICATING WOOD STRUCTURES BACKGROUND OF THE INVENTION This invention relates to apparatus for fabricating wood structures, and is more particularly concerned with apparatus for fabricating shallow depth (e.g., 12-36 inches) flat trusses for use as floor joists and the like.

In conventional construction practice, solid wood members, such as 2 X 12s, are used for floor joists. However, due to increased lumber costs and scarcity of long span lumber of the required dimensions, flat trusses made of less expensive lumber (e.g., 2 X 4s) are becoming increasingly popular for use of floor joists in place of solid wood joists. In addition to utilizing less expensive lumber, trusses are lighter weight and permit considerable labor savings because electrical wiring, plumbing, and ventilation ducts may easily be routed through openings in the truss and thus provide an unobstructed surface at the top and bottom of the trusses to which ceiling or subfloor sheathing, such as wallboard or plywood, may readily be nailed.

While flat roof trusses have been fabricated by apparatus such as shown in my US. Pat. No. 3,693,542, the fabrication of flat floor trusses presents special problems that render many types of roof truss fabricating apparatus unsuitable for floor truss fabrication. More particularly, the relatively shallow depth of floor trusses (for example, floor truss depths may range from 12-36 inches while roof truss depths may range up to 15 feet) require that the apparatus must accommodate trusses of such shallow depth and yet be sufficiently adjustable to support the wood members at the joints of the truss to be formed with the position of the joints varying, depending on the particular truss to be formed. The apparatus of this invention is especially adapted to fabricate shallow depth, flat floor trusses in a rapid and efficient manner at relatively low cost.

SUMMARY OF THE INVENTION Among the several objects of this invention may be noted the provision of apparatus for fabricating shallow depth, flat floor trusses which is adjustable to accommodate trusses of various depths, lengths and configurations; the provision of such apparatus which requires a minimum of floor space; the provision of such apparatus which enables workmen to lay the wood members on a portion of the apparatus to form a first truss while the wood members of a second truss on another portion of the apparatus are being secured together thereby to enable rapid and economical fabrication of trusses; the provision of such apparatus which operates automatically to secure the wood members after they have been properly placed in the apparatus; the provision of such apparatus which lifts a completed truss to facilitate removal of the truss; and the provision of such apparatus which is of rugged construction and relatively low cost. Other objects and features of this invention will be in part apparent and in part pointed out hereinafter.

Briefly, apparatus of this invention for fabricating wood trusses of the type having lower chord members, upper chord members and web members extending from the lower chord members to the upper chorrl members comprises two presses each having an upper and a lower platen which are relatively movable toward and away from one another for driving nailing plates into two or more of the wood members of a truss from above and below, means for supporting the wood members which are to be joined together by the nailing plates, this supporting means including a plurality of supports and means cantilevered relative to each support for holding wood members with clearance therebelow. The apparatus also includes means mounting one of the presses adjacent the upper chord and means mounting the other press adjacent the lower chord for movement of each press along its respective chord into an operating position at a first support for driving nailing plates into the wood members, and for movement in a generally lateral direction with respect to the press sidewise out of its operating position at said first support and into its operating position at a next successive support along its respective chord. Each press is movable along its respective chord independently of the other, and means is provided for controlling movement of each of the press mounting means including means movable therewith for sensing the approach of the press to its operating position at a support in advance of its arrival at its operating position thereby to initiate deceleration of the mounting means and for sensing the arrival of the press at its operating position at the lastsaid support so as to stop movement of the press at its operating position for driving nailing plates into the wood members.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of apparatus of thisinvention having two frames arranged end-to-end, each frame holding wood members which are to be secured together to form a floor truss;

FIG. 2 (sheet 2) is a partial perspective of one of the frames supporting wood members and showing a pair of presses movable along the upper and lower chords of the truss for driving nailing plates into the wood members;

FIG. 3 (sheet 6) is an enlarged plan view of one of the frames of FIG. 1;

FIG. 4 is a front elevational view of the frame of FIG.

FIG. 5 is an enlarged vertical section on line 5--5 of FIG. 4;

FIG. 6 is an enlarged partial perspective of one of the frames showing means for lifting a completed truss clear of the supports to facilitate removal of the completed truss;

FIG. 7 is an enlarged side elevation of the truss lifting means; FIG. 8 is an enlarged view taken on line 8-'8 of FIG. 3 of one of the supports;

FIG. 9 is an enlarged partial plan view taken on line 9-9 of FIG. 4 illustrating means for clamping the wood members in position for being secured together by nailing plates;

FIG. 10 is a side elevation of a press carriage;

FIG. 11 is a block diagram of means for controlling operation of the press and press carriage; and

FIGS. 12 and 13 are electrical schematics of means for controlling operation of the apparatus.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, apparatus of this invention, indicated in its entirety at I, is shown in FIG. 1 for fabricating wood trusses T of the type having lower chord members LC, upper chord members UC and web members W extending from the lower chord members to the upper chord members. More particularly, apparatus of this invention is especially useful for fabricating flat, shallow-depth trusses made of 2 X 4 commercially available lumber for use as floor joists. The trusses shown in the drawings have duct openings DO formed at the midpoint of the truss to permit ventilating ducts to be routed between the upper and lower chords. Duct openings D are defined by a pair of spaced-apart vertical inner web members VW, one on each side of the midpoint of the truss, and by the upper and lower chords. It will be understood, however, that apparatus of this invention may also be utilized to fabricate trusses of other configurations without the abovesaid duct openings, and with suitable modification to fabricate other types of wood structures, such as wall sections having upper and lower plate members with wall studs extending perpendicularly therebetween and secured thereto by nailing plates with the upper and lower plates corresponding generally to the upper and lower chords UC and LC and with the studs corresponding generally to the webs W of truss T. Apparatus 1 comprises a pair of presses, as indicated at 30, 3b, each having an upper platen 5 and a lower platen 7 (see FIGS. 5 and 10) which are relatively movable toward and away from one another for driving nailing plates N into two or more of the wood members from above and below (see FIG. 8) thereby to rigidly secure the wood members together at the joints of the truss. The apparatus further includes means, as indicated generally at 9, including a plurality of lumber platforms or supports 11 and arms 13 cantilevered from each support for holding the wood members in position so that they may properly be joined together by nailing plates N, the support and the cantilever arms together constituting cantilever means. In FIGS. 2 and 5, it can be seen that the cantilevered arms 13 support the wood members with clearance for the press below the arms. Each of the presses is mounted on a respective press carriage 15a,

15b movable lengthwise of apparatus 1 along a respective track 17a, 17b adjacent the upper and lower chords, respectively, of a truss for driving nailing plates at each joint along the respective chord of the truss. Each press, as it is carried by its carriage, moves along its track in a generally lateral direction with respect to the press into an operating position (see FIG. 8) at a first support 11 for driving nailing plates into the wood members, and after driving the nailing plates moves generally sidewise out of its operating position at the first support and into its operating position at a next successive support along its respective chord. Each

press

3a, 3b and its respective press carriage 15a, 15b are movable along their respective tracks independently of one another to automatically drive nailing plates at each support along their respective chord. Movement of the presses is controlled by means, generally indicated at 19. Briefly, this controlling means in cludes means 21 (see FIG. 10) movable with each carriage and press for sensing the approach of the press to its operating position at a support from one direction or the other along the chord of the truss in advance of its arrival at its operation to initiate deceleration of the carriage and for sensing the arrival of the press at its operating position at a support so as to stop movement of the press at its operating position and to initiate operation of the press for driving nailing plates into the wood members. After driving nailing plates into the wood members at the first support, the press is automatically moved sidewise out of the first support to its operating position at the next successive support along its respective chord. This is repeated until all the nailing plates have been driven into the wood members along this respective chord.

More particularly, holding means 9 includes a pair of frames 23 (constituting a central support means) arranged end-to-end along a line with each of the frames carrying a series of supports 11 (constituting a series of support means) for holding upper and lower chord members and web members in position for being secured together by nailing plates N to 'form a truss. The inner ends of the frames 23 are spaced apart a sufficient distance (e.g., about 9-10 feet) to allow workmen to walk between the inner end of each frame and the press carriages 15a, 15b when the latter are positioned substantially midway between the frames in a parking position (see FIG. 1). This facilitates the removal of a completed truss from the apparatus. With the frames 23 so arranged, workmen may be positioning wood members on one of the frames while presses 3a, 3b move along the chords of the truss being formed in the other of the frames thereby facilitating rapid production of trusses with a minimum of labor. As shown in FIG. 4, each frame 23 includes a series of posts 25 arranged in a row secured to and extending up from the floor and a horizontal member 27 carried by the upper ends of the posts and extending the length of the frame.

As is shown in FIG. 5, the series of posts 25 and the horizontal member 27 are generally coplanar and they permit the press carriages l5a,l5b 'to pass in close proximity to the center plane of the frame as the press carriages move along the chords of the truss being formed and thus permit shallow-depth trusses to be fabricated. A pair of clamping channels 29 is secured, as by welding, to the upper face of the horizontal member and extends longitudinally thereof for slidably receiving portions of two series or rows of supports 11, one on each side of the center plane of frame 23, for a respective chord of the truss to be fabricated, the supports being movable independently of one another along the length of the frame for being positioned at the joints of a truss to be formed. Also, with this arrangement, the supports are positioned in close back-to-back spaced relation with the cantilever arms 13 extending laterally outwardly of the frame 23. Thus, the supports may be arranged to fabricate trusses of relatively shallow depth.

In FIG. 5, each support (or cantilever means) 11 is shown to comprise a vertical back plate 31 having outwardly facing flange 33 at its lower end engageable with a respective clamping channel 29. Each flange 33 carries means, as indicated at 34, for releasably clamping the support to its respective clamping channel at any position therealong. Arms 13 are cantilevered from the upper margin of the plate in side-by-side spaced relation (see FIG. 8) for supporting wood members on the top surfaces of the arms in position for being secured together by nailing plates N at a location between the arms. As is best shown in FIG. 5, each support is adapted for lateral entry of the lower platen 7 of a

respective press

3a, 3b from one side or the other of the support below the cantilevered arms 13 to its operating position between the arms with the planes of 5 the tops of the arms co-planar and with these planes spaced from the top surface of the lower platen 7 a distance sufficient to accommodate a nailing plate arranged with its teeth pointing upwardly for being driven into the wood members from below (see FIG. 8). The cantilever arms 13 are laterally spaced from one another a distance greater than the width of the lower platen of the press for entry of the lower platen of the press between the arms when the lower platen is moved upwardly to drive a nailing plate N upwardly into the wood members supported on the arms. Each cantilever arm 13 has a pair of inwardly projecting lugs 35 (see FIG. 8) secured thereto adjacent its lower edges for supporting a holder plate 37. These lugs support the holder plate 37 in a manner which permits it to be freely moved upwardly by the lower platen 7 of the press as the lower platen moves upwardly to drive a nailing plate N resting on the holder plate into the wood members from below. With the holder plate resting on the lugs, it is spaced from the woood members a distance sufficient to accommodate a nailing plate N.

The operating position of a

press

3a, 3b at one of the supports 11 is more particularly defined as that position in which the press and its platens are substantially centered with respect to the cantilever arms 13 and the platens are positioned vertically relative to the wood members and fore and aft relative to plate 31 of the support so as to be above and below the joint in the wood members with the lower platen 13 below holder plate 37 when the latter is in its lowered position supported by lugs 35 and with the upper platen 5 above the joint in the wood members. Thus, with the press in its operating position, the press may be operated to drive nailing plates into the wood members without damage to the supports. The operating position of the press is most clearly illustrated in FIGS. 5 and 8.

A stop 39 engageable with the outer face of a respective chord member UC or LC is slidably received by each cantilever arm 13, each stop being movable to any position along the length of its respective arm and being releasably secured to its arm by means of a clamping bolt 41. Stops 39 are positioned on the arms in predetermined positions relative to the center plane of frame 23, with the stops for the lower chord member being spaced from the stops for the upper chord members a distance corresponding to the depth of the truss thereby to prevent outward movement of the chord members during fabrication of the truss. It will be understood that the stops 39 may be positioned to slightly bow the upper and lower chords so that the fabricated truss has a slight bow to compensate for any sag due to the weight of the truss when the truss is placed in the building. Power operated means, indicated at 43 in FIG. 9, is provided for securely holding the upper chord members UC, the lower chord members LC and the web members W in position on supports 11 for being secured together by nailing plates N. Power operated means 43 comprises a pair of opposed air cylinder units 45 each having a ram 47 movable outwardly to ward the ends of the truss. These air cylinder units are secured to a mounting plate 49 which is adapted to be releasably secured to arms 13 of one or more supports 11 so that the air cylinder units are substantially centered with the duct opening D0 of the truss to be formed. Each ram $7 is engageable with the inner face of an adjacent vertical web VW, preferably adjacent the end thereof in contact with the end of an adjacent angled web W. An adjustable stop 51 is carried by an arm 13 of an adjacent support 11 so as to hold the vertical webs VW in position upon actuation of the air cylinder units 45. To initiate clamping of the wood members, a manually operated push-type valve 53 is provided between the air cylinders. Air is supplied to valve 53 by means of an air distribution system 54 included with frame 23 at the center portion thereof. This air distribution system permits the position of the supports 11 readily to be adjusted along clamping channels 29. Upon operation of the valve 53, rams 47 extend to engage the inner faces of their respective vertical webs VW. As each vertical web engages stop 51, continued actuation of the ram causes the other end of the vertical web to push against the adjacent angled web, thus forcing this web into engagement with the inner faces of both the upper and lower chords, and forcing the chords into firm engagement with stops 39, and further forcing the other web members into contact with the inner faces of the chords all along the truss. This clamping force is maintained until all the joints of the truss have been secured by nailing plates N. Each of the air cylinder units 45 is a spring return cylinder for automatically retracting its ram upon venting of air pressure from the cylinder. As is shown in FIGS. 2, 3 and 6, an abutment frame 55 releasably secured to the arms 13 of the outer supports 11 at each end of the truss being formed for preventing endwise movement of the outermost web member relative to the chord members beyond a desired position. The abutment frame 55 is shown in the drawings to be engaged by a vertical end web, but it will be understood that other abutment frames may be used when the outermost web member of the truss is angled rather than vertical. It will also be understood that the arrangement of clamping air cylinders 45 may be adapted for use with trusses having angled innermost web members rather than vertical webs VW. It will be further understood that the poweroperated means 43 may also be constituted by a toggle or scissors linkage actuated by an air cylinder to apply clamping forces to the vertical webs so as to force them endwise of the truss.

As is shown in FIG. 6, means, as indicated at 57, is provided for lifting or ejecting a completed truss T clear of supports 11, stops 39 and. abutment frames 55 so as to facilitate removal of the completed truss from the apparatus. More particularly, lifting means 57 comprises a plurality of lifting or ejector units, each indicated at 59 and each including a mounting bracket 61 releasably secured to frame 23, a lift cylinder unit 63 pivotally carried by the bracket for swinging between a stowed position (see FIGS. 2 and 5) in which the lift cylinder is in line with posts 25 (i.e., substantially within the longitudinal centerplane of holding means 9) so that press carriages 15a, 15b may move past the lift units and a lifting position (see FIG. 6) in which the lift cylinder is swung out from the line of posts 25 and in which its piston rod 65 is movable from a lowered retracted position to a raised lifting position so that an arm 67 carried on the upper end of the lift cylinder piston rod is engageable with one or more of the wood members of the completed truss for lifting it clear of the supports 11 and stops 39. Arm 65 carries a series of rollers 69 engageable with various wood members of the completed truss enabling the truss to be rolled from apparatus after it has been lifted clear of the supports. Lift units 59 also include a swing cylinder unit 71 interconnected between the mounting bracket 61 and lift cylinder 63 for effecting swinging of the lift cylinder between its stowed and lifting positions.

As is shown in FIG. 5, horizontal member 27 has a pair of guide channels 73 secured to its bottom, these channels extending between posts 25. Each mounting bracket 61 has a plurality of clamping lugs 75 at its upper end which are received by the guide channels. Thus, each lifting unit 59 is movable along the horizontal member to any desired position at which its arm 63 may most advantageously engage the wood members for enabling rolling of the truss. Operation of lifting means 57 is effected automatically upon the completion of the truss after the

presses

3a, 3b have moved clear of the truss and after clamping cylinders 45 have been released. Means (not shown) are provided in the air supply system for the lift units which prevents movement of the lift cylinder 61 of each lift unit from its lowered retracted position to its raised lifting position until after its swing cylinder 67 has swung the lift cylinder from its stowed to its lifting position.

Presses

3a and 3b and press carriages a, 15b are essentially identical and for that reason only one press 3b and its respective press carriage 15b need be described in detail. As is shown in FIG. 2, each track means 17a, 17b for the press carriages includes an inverted V- shaped rail 77'adjacent frames 23 and a flat outer rail 79, these rails extending the length of apparatus 1 from one frame 23 to the other. Press carriage 15b comprises a base 81 mounted on a pair of grooved rollers 83 rolling on the inverted V-rail for guiding the carriage along the track, and on a pair of rubber-tire drive wheels 85 engageable with the flat rail 79 for driving the carriage along the track. As is shown in FIG. 5, drive wheels 85 are driven by a reversible hydraulic motor 87, this motor also constituting means for decelerating and stopping the carriage. Base 81 has an electrically driven hydraulic pressure unit generally indicated at 89 mounted thereon including an electric motor M-l, a hydraulic pump and a hydraulic fluid reservoir (see FIG. 10). This hydraulic unit supplies hydraulic fluid under pressure to motor 87 for driving the carriage along the track and for operating press 3b. Power for the electric motor is supplied by means of a respective bus 97 carried by the frames 23. Press 3b includes a C- shaped press frame 97 and a fluid power cylinder 99 operable for effecting movement of the upper platen 5 and the lower platen 7 toward and away from one another. The press also includes means (not shown) for preventing the platens of the press from exerting unequal forces on the arms 13 as the nailing plates N are driven into the wood members, so as to prevent damage to the arms. This last-said means may be of the type shown in the co-assigned U.S. patent application Ser. No. 696,323 now U.S. Patent No. 3,728,958 or other similar means known in the art. The press carriage has a pair of spaced supports 101 extending up from base 81 for mounting the press in position for driving nailing plates into the wood members. The press is mounted c. rollers 103 (see FIG. 5) received in a respective track 104 secured to the upper, inner portions of supports 101 in a manner similar to the way in which the presses in the above-mentioned co-assigned application are mounted in their respective stands, thus enabling the press to be moved in and out relative to frame 23 and thus allowing the top platen 5 to be moved clear of its respective truss chord. Also, rollers 103 permit the press to be moved in and out to fabricate trusses of various depths. At each end of the carriage, a pivoted safety bar 105 is provided for actuating a respective safety switch LS-ll or LS-l3. Upon movement of either safety bar from the position shown in FIG. 2, as may be occasioned by the safety bar striking a person on tracks 17a, 17b as the carriage moves therealong, the carriage is brought to an immediate halt. As a further safety measure, each carriage has a flashing beacon 106 and a warning horn (not shown) operable when the carriage is in operation.

The previously mentioned sensing means 21 for each carriage 15a, 15b further includes means 107 for selectively effecting operation of the sensing means so as to sense the approach of its

respective press

3a, 3b to its operating position at each support 11 from one direction or the other along a chord of the truss being fabricated. Again, carriage 15a and press 3b will be referred to in describing means 21 and 107, but it will be understood that the means 21 and 107 of carriage 15a and press 3a are essentially identical. Briefly, this sensing means comprises two pairs of switches LS-7L and LS- 8R, LS-7R and LS-8L (see FIGS. 10, 11 and 12) carried by the press carriage adjacent the lower platen 7 of its respective press. Switches LS-7L and LS-8R are operable as the press 3b moves from right to left (as viewed in FIG. 2) and switches LS-7R and LS-8L are operable as the press moves from left to right. One switch of each pair is actuated by means, as indicated at 109 in FIG. 5, carried by each support 11 as the press approaches its operating position at a support for initiating deceleration of the press carriage 15b and the other of the switches is actuable by the actuating means 109 for stopping movement of the press carriage along the track 17b with the press in its operating position at one of the supports 11. With both of the switches actuated, circuits, as will appear, are energized to initiate closing of the press to drive nailing plates N into the wood members. Preferably, switches LS-7L, LS-8R, LS-7R and LS-8L are magnetic proximity switches of the type actuable in response to a magnetic field of a predetermined strength, and the actuating means 109 comprises a pair of magnets 111a, lllb (see FIG. 8) secured to plate 31 at each of the supports. As is shown in FIG. 5, magnets 111a, lllb and the magnetic switches are positioned on the support and on the press carriage so that the switches pass in close proximity to the magnets as the press carriage moves along the track thereby to actuate the switches as they pass by the magnets. As is shown in FIG. 10, the switches of each pair are spaced apart a predetermined distance (about 18-20 inches) and the magnets 111a, lllb on each of the supports are spaced a corresponding distance so that when the press is in its operating position, both switches of each pair are actuated by the magnets. Although magnetic switches are shown, it will be understood that mechanically operated limit switches or other proximity sensing means (e.g., photoelectric cells) may also be used.

Referring to the block diagram of the sensing means 21 shown in FIG. 11, operation of the sensing means may more fully be explained. Starting with both press carriages a, 15b in their parked positions between the adjacent ends of frames 23 and with the wood members clamped to the supports 11 of the left frame (as viewed in FIG. 1), operation of each of the press carriages is initiated by operating a lever or joystick" 113 (see FIG. 2). As can be seen in FIGS. 12 and 13, movement of the carriage to the right or left is controlled by lever 113 and this lever thus constitutes means 107 for effecting operation of sensing means 21 so as to sense the approach of the press to its operating position from either direction along the chord of the truss to be fabricated. Operation of lever 113 initiates an automatic carriage cycle which causes each of the press carriages to accelerate from its parked position toward the first support 11 of the left frame 23. Again, only movement of carriage 15b need be described as movement of carriage 15a is essentially identical. As the lower platen 7 of the press moves under the arms 13 of the first support 1], switch LS-7L is energized by the magnet lllb on the right side of the first support to decelerate, but not stop, the press carriage by reducing the flow of hydraulic fluid to hydraulic motor 87, and thus exerting a braking force on the carriage. The carriage continues to move slowly to the left until the rightmost switch, LS-8R, is actuated by the magnet lllb thereby to brake the carriage to a halt with its

press

3a, 3b properly docked or positioned at its operation between arms 13. With the press so positioned, switch LS-7L is actuated by the left magnet 111a, and the switch LS-SR is actuated by the right magnet lllb. With both switches actuated, the operating position of the press is verified and operation of the press is initiated to automatically drive nailing plates N into the wood members at the first support. After the maximum hydraulic pressure has been applied to fluid cylinder 99 of the press, thereby indicating the nailing plates have been driven fully into the wood members, the press is automatically opened. As the platens are moved to their fully open positions, a switch LS-lO is tripped to initiate the next automatic press carriage cycle. The automatic press carriage cycle are automatic press cycle are repeated until the press carriage has moved succesively from the first support to the last or outermost support along the left frame 23. As each carriage approaches the last support 11, a magnetic switch LS-2 (referred to as a reverse switch) carried by the carriage is actuated by a magnet (not shown) on the last support. After the automatic press cycle at the last support, the reverse switch causes the press to return to its parked position. Upon approaching its parked position, a switch LS-S is energized causing the carriage to decelerate. The carriage continues to travel to the right until it reaches its parked position, when a park position switch LS-16 is actuated. This switch LS-16 stops the carriage in its parked position. When both carriages 15a, 15b have returned to their parked positions and their respective switches LS-16 are tripped, release of wood clamping cylinders 45 and operation of the lift units 59 are initiated to lift the completed truss clear of the supports 11 and stops 39 to facilitate removal of the truss. The press carriage is then ready for re-cycling.

The operation of the press carriage control means 19 15b will be apparent to one skilled in the art. In FIGS. 12 and 13, 8-1, 8-2, 5-3 etc. indicate manually actuated swtiches, LS-2, LS-S, LS-7 etc. indicate automatically actuated switches, relay coils are: indicated as CR-l, CR-Z, CR-3, etc. with the relay contacts indicated as CR-lD, CR-2D etc., time delay relays are indicated at TR-S, TR-6 etc. with time delay relay contacts indicated as TR6A, TR-SD etc., and pressure actuated switches are indicated at PS1 and PS-2.

It will be noted if the press carriages 15a, 15b are moved slowly along their respective tracks 17a, 17b, it may be possible to stop movement of the carriage with their

respective press

3a,3b properly positioned at its operating position at a support 11 without first sensing the approach of the press to its operating position and initiating deceleration of the carriage. It will also be noted that means other than hydraulic motor 87 may be used to drive the carriage along the track. For example, a chain (not shown) may be attached to the carriage, the chain extending along the length of the track from both sides of the carriage and being movable by a power driven sprocket remote from the carriage operable to effect movement of the press from its operating position at one stand to another, with controlling means 19 being operable to control the above-said sprocket thereby to effect movement of the press carriage along its track from its operating position in one support to its operating position at each successive support.

In view of the above, it will be :seen that the several objects of the invention are achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. Apparatus for fabricating wood structures, such as trusses of the type having lower chord members, upper chord members and web members extending from the lower chord members to the upper chord members, said apparatus comprising two presses each having an upper and a lower platen which are relatively movable toward and away from one another for driving nailing plates into two or more of the wood members of a truss from above and below, means for supporting the wood members which are to be joined together by said nailing plates, said supporting means including a plurality of supports and means cantilevered relative to each support for holding wood members with clearance therebelow, means mounting one of the presses adjacent said upper chord and means mounting the other press adjacent said lower chord for movement of each press along its respective chord into an operating position at a first support for driving nailing plates into the wood members, and for movement in a generally lateral direction with respect to the press sidewise out of its operating position at said first support and into its ating position thereby to initiate deceleration of said.

mounting means and for sensing the arrival of the press at its operating position at the last-said support so as to stop movement of the press at itsoperating position for driving nailing plates into the wood members.

2. Apparatus as set forth in claim 1 wherein said sensing means further includes means for sensing the approach of the press to its operating position at each support from one direction along its respective chord and for sensing registration of the press at its operating position at each support, and means for effecting operation of said sensing means so as to sense the approach of said press to its operating position at each support from the other direction along its respective chord.

3. Apparatus as set forth in claim 2 wherein said sensing means further comprises actuating means at each support and switch means carried along with the press, said switch means being actuable by said actuating means as the press approaches its operating position at a support for initiating deceleration of the press mounting means and being further actuable by the actuating means for stopping movement of the press mounting means with the press in its operating position at one of said supports.

.4. Apparatus as set forth in claim 3 wherein said switch means comprises a first proximity switch carried along with the press actuable by said actuating means as the press approaches its operating position at a support for initiating deceleration of the press mounting means and a second proximity switch carried along with the press actuable by said actuating means for stopping the press mounting means when the press is in its operating position at a support.

5. Apparatus as set forth in claim 4 wherein said first and second proximity switches are magnetic switches actuable in response to a magnetic field of a predetermined strength, and wherein said actuating means at each support comprises at least one magnet of sufficient strength to actuate said first and second proximity switches as they move past the magnet, said magne. being positioned on the support and said proximity switches being positioned on the carriage so that said proximity switches pass in close spaced relation to the magnet as the press approaches and moves into its operating position.

6. Apparatus as set forth in claim 5 wherein said actuating means comprises a pair of said magnets, said proximity switches being spaced apart a predetermined distance and said magnets being spaced on the support a distance corresponding to the spacing of the proximity switches so that with the press in its operating position both of said switches are actuated by said magnets so as to stop the press in its operating position and so as to initiate operation of the press for driving nailing plates into the wood members.

7. Apparatus as set forth in claim 2 wherein said supporting means comprises a first frame and a second frame, each frame carrying a series of supports for holding said upper chord members, lower chord members and web members in position for being secured together by nailing plates so as to fabricate a truss on the supports of each of the frames, said frames being arranged in end-to-end relation relative to one another :2 that said presses carried by said press mounting means may move along the chords of respective trusses to be formed on each frame for driving nailing plates into the wood members at the joints of the trusses to be fabricated.

8. Apparatus as set forth in claim 7 wherein the supports for the upper chord members and the supports for the lower chord members on each said frame and arranged in close back-to-back spaced relation and are movable relative to one another longitudinally along their respective frame.

9. Apparatus as set forth in claim 8 wherein each support comprises a vertically disposed plate extending up from said frame, and wherein said cantilevered means comprises two cantilevered arms in side-by-side spaced relation adapted to support wood members in position for being secured together by the nailing plates at a location between the arms, said support being adapted for lateral entry of the lower platen of one of the presses from one side or the other thereof below said cantilevered arms to its operating position between said arms with the planeof the top surfaces of the arms spaced from the top surface of the lower platen a distance sufficient to accommodate a nailing plate arranged with its teeth pointing upwardly for being driven into the wood members from below, the cantilever arms being laterally spaced from one another a distance greater than the width of the lower platen of the press for entry of the lower platen of the press between the arms when the lower platen is moved upwardly to drive the nailing plate upwardly into the wood members.

10. Apparatus as set forth in claim 8 further comprising track means on each side of said frames extending from the outer end of the first frame to the outer end of the second frame, each said press mounting means comprising a power driven carriage movable in one direction along its respective track means for moving its respective press to its operating position at one of the supports carried by said first frame into its operating positions at each successive support along its respective chord of the first frame and movable in the other direction along its respective track means for moving its press to its operating position at one of the supports carried by the second frame and to its operating positions at each successive support along its respective chord of said second frame.

11. Apparatus as set forth in claim 10 wherein said first and second frames are arranged in a line and are spaced apart from one another, wherein each of said press carriages is initially positioned at a parking position between the frames and wherein, upon the initiation of movement of said carriage in said one direction along its respective track means, said press is automatically moved in said one direction along its track means from its parking position to its operating position at a first support adjacent the inner end of said first frame for driving the nailing plates into the wood members at said first support of said first frame and then is automatically movable to its operating position at each successive support along its respective chord of said first frame until all joints along its respective chord have been secured together, said press carriage then being automatically movable to its parking position, and upon initiation of movement of the press carriage in said other direction along its respective track means, said press is automatically moved from its parking position to its operating position at a first support adjacent the inner end of said second frame for driving nailing plates into the wood members at said first support of said second frame and is automatically moved to its operating position at each successive support along its respective chord of said second frame until all joints along its respective chord have been secured together, said press carriage then being automatically movable to its parking position.

12. Apparatus as set forth in claim 1 wherein said supporting means further comprises a frame for carrying a plurality of said supports with the supports for the upper chord members and the supports for the lower chord members being in close back-to-back spaced relation and being movable relative to one another longitudinally along said frame.

13. Apparatus as set forth in claim 12 wherein each support includes means for securing it to said frame at any position therealong.

14. Apparatus as set forth in claim 13 wherein each support comprises a vertically disposed plate extending up from said frame, and wherein said cantilevered means comprises two cantilevered arms in side-by-side spaced relation adapted to support wood members in position for being secured together by the nailing plates at a location between the arms, said support being adapted for lateral entry of the lower platen of a press from one side or the other thereof below said cantilevered arms to its operating position between said arms with the plane of the top surfaces of the arms spaced from the top surface of the lower platen a distance sufficient to accommodate a nailing plate arranged with its teeth pointing upwardly for being driven into the wood members from below, the cantilever arms being laterally spaced from one another a distance greater than the width of the lower platen of the press for entry of the lower platen of the press between the arms when the lower platen is moved upwardly to drive a nailing plate upwardly into the wood members.

15. Apparatus as set forth in claim 14 further comprising track means on each side of said frame parallel to said upper and lower chords of the truss to be fabricated, and wherein each said press mounting means comprises a power driven carriage movable along a respective track means for moving its press from its operating position at one of said supports to its operating position at each successive support along its respective chord.

16. Apparatus as set forth in claim 1, further comprising means for lifting a completed truss clear of said support, said lifting means being swingable from a stowed position in which it permits movement of said press mounting means therepast, and a lifting position in which it is engageable with one or more wood members of a fabricated truss for lifting the completed truss clear of the supports.

17. Apparatus as set forth in claim 16 wherein said lifting means includes a plurality of rollers engageable with the completed truss to enable rolling of the completed truss from the apparatus when it is lifted clear of the supports.

18. Apparatus as set forth in claim 17 wherein said lifting means comprises a plurality of lifting units each comprising a mounting bracket adapted to be secured to said main frame, a lift cylinder unit pivotally carried by said bracket for swinging between said stowed position and said lifting position, and a swing cylinder un t for effecting swinging of the lift cylinder unit between its stowed and lifting positions, said lift cylinder having an arm engageable with members of the completed truss, said arm being movable between a lowered retracted position and a raised position in which it is engageable with the completed truss for lifting it clear of the supports.

19. Apparatus as set forth in claim 18 wherein said lifting means includes means for preventing movement of the lift cylinder unit from its lowered retracted position to its raised position until said swing cylinder unit has fully swung the lift cylinder unit from its stowed to its lifting position.

20. Apparatus as set forth in claim 18 wherein said arm has a plurality of rollers engageable with various wood members of said completed truss enabling rolling of the completed truss from the apparatus after it has been lifted clear of the supports.

21. Apparatus as set forth in claim 1 wherein the truss to be fabricated is a flat truss with its upper and lower chords substantially parallel to one another, with the innermost web members of the truss substantially perpendicular to the chords, and with others of the webs angled with respect'to the chords and having their ends in contact with the ends of adjacent webs and with the inner faces of said chord members, said apparatus further comprising means for clamping said chord members and web members in position so as to be rigidly secured together by nailing plates, said clamping means comprising a plurality of stops carried by said cantilever means engageable by the outer faces of the chord members thereby to hold the chord members in desired spaced relation, and power operated means engageable with the opposed inner faces of said vertical webs for applying a force thereagainst so as to force all the web members into abutting relation with one another and with the inner faces of the chord members from one end of the truss to the other and to hold the chord members in abutting relation with said stops, and means at each end of the truss for preventing endwise movement of the outermost web member relative to the chord members beyond a desired position.

22. Apparatus for fabricating flat wood trusses of the type having lower chord members, upper chord members and web members extending from the lower chord members to the upper chord members, with said upper and lower chord members substantially parallel to one another, with the innermost web members substantially perpendicular to the chord members and with the other of the webs angled with respect to the chords and having their ends in contact with the ends of adjacent web members and with the inner faces of said chord members, said apparatus comprising means for driving nailing plates into two or more of the wood members of a truss, means for holding the wood members in position for being joined together by said nailing plates including a series of supports, and means for clamping said chord members and web members in position so as to be rigidly secured together by nailing plates, said clamping means comprising a series of stops carried by said supports engageable by the outer faces of said chord members thereby to hold the chord members in desired spaced relation, and power operated means engageable with the faces of each of said perpendicular webs facing one another for applying a force thereagainst so as to force all the web members into abutting relation with one another and with the inner faces of the chord members from one end of the truss to the other and to hold the chord members in abutting rela tion with said stops, and means at each end of the truss for preventing endwise movement of the outermost web member relative to the chord members beyond a desired position.

23. Apparatus for fabricating wood structures, such as trusses of the type having lower chords, upper chords and web members extending between the chords, said apparatus utilizing at least one press having an upper platen and a lower platen which are relatively movable toward one another for driving nailing plates into two or more of the wood members at the joints of said truss thereby to rigidly secure the wood members together, said apparatus comprising means for holding said wood members in position for being secured together by said nailing plates, means mounting the press for movement along one chord of the truss to be fabricated in close proximity to the holding means for driving nailing plates into the wood member at each joint along said one chord of the truss, and lifting means carried by said holding means swingable between a stowed position substantially in the longitudinal vertical centerplane of said holding means in which said press mounting means and said press may move therepast and a lifting position substantially perpendicular to said centerplane and in the path of said press as the latter moves along said one chord in which said lifting means is engageable with one or more of the wood members of the completed truss for lifting the completed truss clear of said holding means.

24. Apparatus for fabricating wood structures, such as trusses of the type having lower chords, upper chords and web members extending between the chords, said apparatus utilizing at least one press having an upper platen and a lower platen which are relatively movable toward one another for driving nailing plates into two or more of the wood members at the joints of said truss thereby to rigidly secure the wood members together, said apparatus comprising means constituting supports for holding said wood members in position for being secured together by said nailing plates, means mounting the press for movement along one chord of the truss to be fabricated in close proximity to the holding means for driving nailing plates into the wood member at each joint along said one chord of the truss, and lifting means carried by said holding means swingable between a stowed position in which said press mounting means may move therepast and a lifting position in which it is engageable with one or more of the wood members of the completed truss for lifting the completed truss clear of said supports, said lifting means further comprising a plurality of lifting units each having a mounting bracket adapted to be secured to said frame, a lift cylinder unit pivotally carried by said bracket for swinging between said stowed position and said lifting position, and a swing cylinder unit for effecting swinging of the lift cylinder unit between its stowed and lifting positions, said lift cylinder unit having an arm engageable with members of the completed truss, said arm being movable between a lowered retracted position and a raised position in which it is engageable with the completed truss for lifting it clear of the supports.

Apparatus as set forth in claim 24 wherein said lifting means includes means for preventing movement of the lift cylinder unit from its lowered retracted pottion to its raised position until said swing cylinder unit has fully swung the lift cylinder unit from its stowed to its lifting position.

26. Apparatus as set forth in claim 25 wherein said arm has a plurality of rollers engageable with various wood members of said completed truss enabling rolling of the completed truss from the apparatus after it has been lifted clear of the supports.

27. Apparatus for fabricating wood structures, such as trusses of the type having lower chord members, upper chord members and web members extending from the lower chord members to the upper chord members, said apparatus comprising a press having an upper and a lower platen which are relatively movable toward and away from one another for driving nailing plates into two or more of the wood members of a truss from above and below, means for supporting the wood members which are to be joined together by said nailing plates, said supporting means including a plurality of supports and means cantilevered relative to each support for holding wood members with clearance therebelow, means mounting the press adjacent one of said chords for movement of the press from one direction or the other along its respective chord into an operating position at a first support for driving nailing plates into the wood members, and for movement in a generally lateral direction with respect to the press sidewise out of its operating position at said first support and into its operating position at a next successive support along its respective chord, means for controlling movement of the press mounting means including means movable therewith for sensing the approach of said press from one direction along its respective chord to its operating position at a support in advance of its arrival at its operating position thereby to initiate deceleration of said mounting means and for sensing the arrival of the press at its operating position at the lastsaid support so as to stop movement of the press as its operating position for driving nailing plates into the wood members, and means for effecting reversal of said sensing means to sense the approach of said press from the other direction along its respective chord to its operating position at a support in advance of its arrival at its operating position at the last-said support thereby to initiate deceleration of said mounting means and for sensing the arrival of the press at its operating position at the last-said support so as to stop movement of the press at its operating position for driving nailing plates into the wood members.

28. Apparatus for fabricating wood structures, such as trusses of the type having lower chord members, upper chord members and web members extending from the lower chord members to the upper chord members, said apparatus comprising two presses each having an upper and a lower platen which are relatively movable toward and away from one another for driving nailing plates into two or more of the wood members of a truss from above and below, a first and second series of support means for supporting the wood members which are to be joined together by said nailing plates, each series including central supporting means and cantilevered means extending laterally outwardly therefrom on opposite sides thereof, said cantilever means being arranged in two rows, one on each lateral side of the central supporting means for holding members with clearance for the lower platens of the presses therebelow, said first and second series being arranged in a line in end-to-end relation relative to one another, means mounting each of the presses, one press on one side of said line and the other press on the other side of said line, for movement of the presses independently of one another along said rows, for movement of each press into an operating position at a respective cantilever means so as to drive nailing plates into the members, and for movement in a generally lateral direction with respect to the press sidewise out of its operating position at said cantilever means and into its operating position at a next successive cantilever means, said series being spaced apart from one another so that with said press mounting means positioned between the first and second series in a parking position, a workman may walk between the ends of either series and the press mounting means.

29. Apparatus as set forth in claim 28 further comprising means for controlling movement of each press mounting means along its respective said row, operable to stop the press at its operating position at each of said cantilever means for driving nailing plates into the members.

30. Apparatus as set forth in claim 29 wherein said cantilever means are arranged in close back-to-back spaced relation and are movable relative to one another longitudinally along said line to different positions.

31. Apparatus as set forth in claim 29 wherein each cantilever means comprises a vertically disposed plate extending up from said frame, and two cantilevered arms in side-by-side spaced relation adapted to support wood members in position for being secured together by the nailing plates at a location between the arms, said cantilever means being adapted for lateral entry of the lower platen of one of the presses from one side or the other thereof below said cantilevered arms to its operating position between said arms with the plane of the top surfaces of the arms spaced from the top surface of the lower platen a distance sufficient to accommodate a nailing plate arranged with its teeth pointing upwardly for being driven into the wood members from below, the cantilever arms being laterally spaced from one another a distance greater than the width of the lower platen of the press for entry of the lower plater of the press between the arms when the lower platen is moved upwardly to drive the nailing plate upwardly into the wood members.

32. Apparatus as set forth in claim 29 further comprising track means on each side of said line extending from the outer end of the first series to the outer end of the second series, each said press mounting means comprising a power driven carriage movable in one direction along its respective track means for moving its respective press to its operating position at each successive cantilever meansalong each of said series.

33. Apparatus as set forth in claim 32 wherein, with said press carriages initially positioned in their parking positions between said series and wherein upon the initiation of movement of one of said carriages in said one direction along its respective track means, the press of said one carriage is automatically moved in said one direction along its track means from its parking position to its operation position at a cantilever means adjacent the inner end of said first series for driving nailing plates into the wood members at said first cantilever means and then is automatically movable to its operating position at each successive cantilever means along said first series until all joints therealong have been secured together, said press carriage then being automatically movable to its parking position, and upon initiation of movement of the press carriage in said other direction along its respective track means, said press is automatically moved from its parking position to its operating position at a first cantilever means adjacent the inner end of said second series for driving nailing plates into the wood members at said first cantilever means of said second series and is automatically movable to its operating position at each successive cantilever means along said second series until all joints therealong have been secured together, said press carriage then being automatically movable to its parking position.

34. Apparatus as set forth in claim 28 further comprising means for lifting a completed truss from said supporting means of each of said frames, and means for preventing operation of said lifting means when oneof said press mounting means is moved from its parking position.

Claims

1. Apparatus for fabricating wood structures, such as trusses of the type having lower chord members, upper chord members and web members extending from the lower chord members to the upper chord members, said apparatus comprising two presses each having an upper and a lower platen which are relatively movable toward and away from one another for driving nailing plates into two or more of the wood members of a truss from above and below, means for supporting the wood members which are to be joined together by said nailing plates, said supporting means including a plurality of supports and means cantilevered relative to each support for holding wood members with clearance therebelow, means mounting one of the presses adjacent said upper chord and means mounting the other press adjacent said lower chord for movement of each press along its respective chord into an operating position at a first support for driving nailing plates into the wood members, and for movement in a generally lateral direction with respect to the press sidewise out of its operating position at said first support and into its operating position at a next successive support along its respective chord, each said press being movable along its respective chord independently of the other, and means for controlling movement of each of the press mounting means including means movable therewith for sensing the approach of said press to its operating position at a support in advance of its arrival at its operating position thereby to initiate deceleration of said mounting means and for sensing the arrival of the press at its operating position at the last-said support so as to stop movement of the press at its operating position for driving nailing plates into the wood members.

4. Apparatus as set forth in claim 3 wherein said switch means comprises a first proximity switch carried along with the press actuable by said actuating means as the press approaches its operating position at a support for initiating deceleration of the press mounting means and a second proximity switch carried along with the press actuable by said actuating means for stopping the press mounting means when the press is in its operating position at a support.

5. Apparatus as set forth in claim 4 wherein said first and second proximity switches are magnetic switches actuable in response to a magnetic field of a predetermined strength, and wherein said actuating means at each support comprises at least one magnet of sufficient strength to actuate said first and second proximity switches as they move past the magnet, said magnet being positioned on the support and said proximity switches being positioned on the carriage so that said proximity switches pass in close spAced relation to the magnet as the press approaches and moves into its operating position.

7. Apparatus as set forth in claim 2 wherein said supporting means comprises a first frame and a second frame, each frame carrying a series of supports for holding said upper chord members, lower chord members and web members in position for being secured together by nailing plates so as to fabricate a truss on the supports of each of the frames, said frames being arranged in end-to-end relation relative to one another so that said presses carried by said press mounting means may move along the chords of respective trusses to be formed on each frame for driving nailing plates into the wood members at the joints of the trusses to be fabricated.

9. Apparatus as set forth in claim 8 wherein each support comprises a vertically disposed plate extending up from said frame, and wherein said cantilevered means comprises two cantilevered arms in side-by-side spaced relation adapted to support wood members in position for being secured together by the nailing plates at a location between the arms, said support being adapted for lateral entry of the lower platen of one of the presses from one side or the other thereof below said cantilevered arms to its operating position between said arms with the plane of the top surfaces of the arms spaced from the top surface of the lower platen a distance sufficient to accommodate a nailing plate arranged with its teeth pointing upwardly for being driven into the wood members from below, the cantilever arms being laterally spaced from one another a distance greater than the width of the lower platen of the press for entry of the lower platen of the press between the arms when the lower platen is moved upwardly to drive the nailing plate upwardly into the wood members.

18. Apparatus as set forth in claim 17 wherein said lifting means comprises a plurality of lifting units each comprising a mounting bracket adapted to be secured to said main frame, a lift cylinder unit pivotally carried by said bracket for swinging between said stowed position and said lifting position, and a swing cylinder unit for effecting swinging of the lift cylinder unit between its stowed and lifting positions, said lift cylinder having an arm engagEable with members of the completed truss, said arm being movable between a lowered retracted position and a raised position in which it is engageable with the completed truss for lifting it clear of the supports.

21. Apparatus as set forth in claim 1 wherein the truss to be fabricated is a flat truss with its upper and lower chords substantially parallel to one another, with the innermost web members of the truss substantially perpendicular to the chords, and with others of the webs angled with respect to the chords and having their ends in contact with the ends of adjacent webs and with the inner faces of said chord members, said apparatus further comprising means for clamping said chord members and web members in position so as to be rigidly secured together by nailing plates, said clamping means comprising a plurality of stops carried by said cantilever means engageable by the outer faces of the chord members thereby to hold the chord members in desired spaced relation, and power operated means engageable with the opposed inner faces of said vertical webs for applying a force thereagainst so as to force all the web members into abutting relation with one another and with the inner faces of the chord members from one end of the truss to the other and to hold the chord members in abutting relation with said stops, and means at each end of the truss for preventing endwise movement of the outermost web member relative to the chord members beyond a desired position.

22. Apparatus for fabricating flat wood trusses of the type having lower chord members, upper chord members and web members extending from the lower chord members to the upper chord members, with said upper and lower chord members substantially parallel to one another, with the innermost web members substantially perpendicular to the chord members and with the other of the webs angled with respect to the chords and having their ends in contact with the ends of adjacent web members and with the inner faces of said chord members, said apparatus comprising means for driving nailing plates into two or more of the wood members of a truss, means for holding the wood members in position for being joined together by said nailing plates including a series of supports, and means for clamping said chord members and web members in position so as to be rigidly secured together by nailing plates, said clamping means comprising a series of stops carried by said supports engageable by the outer faces of said chord members thereby to hold the chord members in desired spaced relation, and power operated means engageable with the faces of each of said perpendicular webs facing one another for applying a force thereagainst so as to force all the web members into abutting relation with one another and with the inner faces of the chord members from one end of the truss to the other and to hold the chord members in abutting relation with said stops, and means at each end of the truss for preventing endwise movement of the outermost web member relative to the chord members beyond a desired position.

25. Apparatus as set forth in claim 24 wherein said lifting means includes means for preventing movement of the lift cylinder unit from its lowered retracted position to its raised position until said swing cylinder unit has fully swung the lift cylinder unit from its stowed to its lifting position.

27. Apparatus for fabricating wood structures, such as trusses of the type having lower chord members, upper chord members and web members extending from the lower chord members to the upper chord members, said apparatus comprising a press having an upper and a lower platen which are relatively movable toward and away from one another for driving nailing plates into two or more of the wood members of a truss from above and below, means for supporting the wood members which are to be joined together by said nailing plates, said supporting means including a plurality of supports and means cantilevered relative to each support for holding wood members with clearance therebelow, means mounting the press adjacent one of said chords for movement of the press from one direction or the other along its reSpective chord into an operating position at a first support for driving nailing plates into the wood members, and for movement in a generally lateral direction with respect to the press sidewise out of its operating position at said first support and into its operating position at a next successive support along its respective chord, means for controlling movement of the press mounting means including means movable therewith for sensing the approach of said press from one direction along its respective chord to its operating position at a support in advance of its arrival at its operating position thereby to initiate deceleration of said mounting means and for sensing the arrival of the press at its operating position at the last-said support so as to stop movement of the press as its operating position for driving nailing plates into the wood members, and means for effecting reversal of said sensing means to sense the approach of said press from the other direction along its respective chord to its operating position at a support in advance of its arrival at its operating position at the last-said support thereby to initiate deceleration of said mounting means and for sensing the arrival of the press at its operating position at the last-said support so as to stop movement of the press at its operating position for driving nailing plates into the wood members.

31. Apparatus as set forth in claim 29 wherein each cantilever means comprises a vertically disposed plate extending up from said frame, and two cantilevered arms in side-by-side spaced relation adapted to support wood members in position for being secured together by the nailing plates at a location between the arms, said cantilever means being adapted for latEral entry of the lower platen of one of the presses from one side or the other thereof below said cantilevered arms to its operating position between said arms with the plane of the top surfaces of the arms spaced from the top surface of the lower platen a distance sufficient to accommodate a nailing plate arranged with its teeth pointing upwardly for being driven into the wood members from below, the cantilever arms being laterally spaced from one another a distance greater than the width of the lower platen of the press for entry of the lower platen of the press between the arms when the lower platen is moved upwardly to drive the nailing plate upwardly into the wood members.

32. Apparatus as set forth in claim 29 further comprising track means on each side of said line extending from the outer end of the first series to the outer end of the second series, each said press mounting means comprising a power driven carriage movable in one direction along its respective track means for moving its respective press to its operating postion at each successive cantilever means along each of said series.

34. Apparatus as set forth in claim 28 further comprising means for lifting a completed truss from said supporting means of each of said frames, and means for preventing operation of said lifting means when one of said press mounting means is moved from its parking position.