US3361097A

US3361097A - Button stitching machine

Info

Publication number: US3361097A
Application number: US407138A
Authority: US
Inventors: Pedersen Mathias; Robert J Cook
Original assignee: AMF Inc
Current assignee: AMF Inc
Priority date: 1964-10-28
Filing date: 1964-10-28
Publication date: 1968-01-02
Anticipated expiration: 1985-01-02

Description

Jan. 2, 196 8 I PEDERSEN ET AL 3,361,097

BUTTON STITCHING MACHINE Filed Oct. 28, 1964 4 Sheets-Sheet 1 I V FIG.

INVENTORS MATHIAS PEDERSEN BY ROBERT J. COOK ATTORNEY 1968 M. PEDERSEN ET L BUTTON STITCHING MACHINE Filed Oct. 28, 1964 4 Sheets-Sheet INVENTORS MATHIAS PEDERSEN ROBERT J. COOK ATTORNEY Jan. 2, 1968 M. PEDERSEN ET AL BUTTON STITCHING MACHINE 4 Sheets-Sheet 5 Filed Oct. 28, 1964 INVENTQRS MATHIAS PEDERSEN Y ROBERT J COOK ATTORNEY M. PEDERSEN ET AL 3,361,097

BUTTON STITCHING MACHINE 4 Sheets-Sheet 4 INVENTQRS MATHIAS PEDERSEN BY ROBERT J. COOK Ai'TORNEY Jan. 2, 1968 Filed Oct. 28, 1964 United States Patent 3,361,097 BUTIQN STlTCI-IING MACHINE Mathias Pedersen, Valley Stream, and Robert J. Cook, Westbury, N.Y., assignors to American Machine & Foundry Company, a corporation of New Jersey Filed Oct. 28, 1964, Ser. No. 407,138 Claims. (Cl. 112-110) ABSTRACT OF THE DISCLOSURE A button stitching machine for sewing a button to an article of clothing having a table for supporting the clothing work and a button to be attached thereto, opposed needle bars for passing a threaded needle back and forth through selected button holes and said work, and forming wrappings of thread about said loops of thread to produce a post connecting said button to said work, and locking stitches in said post, and mechanism for moving said table to position said Work and said button relative to said needle in accordance with a predetermined stitching pattern; the combination with said table moving mechanism of means for selectively controlling said mechanism to limit the extent of movement of said table toward said needle during the formation of said locking stitches to cause said needle to be passed back and forth through said post in a position substantially equi-distant between the surface of said work and the undersurface of said button.

This invention relates to stitching machines, and more particularly to machines for stitching or sewing buttons or like fastening devices to articles of clothing, such as mens and Womens coats, and to other selected types of goods.

The invention relates to button stitching machines of the type disclosed in Patterson et a1. Patent 2,739,550; Johnson at a]. Patent 3,123,613, granted May 12, 1964; Johnson et a1. Patent 3,121,411, granted Feb. 18, 1964; Pedersen Patent 3,125,046, issued Mar. 17, 1964, for Work Support Table for Button Stitching Machine, and copending Johnson application Ser. No. 296,039, now Patent No. 3,236,200, filed July 18, 1963, for Button Stitching Machine.

In the garment trade different sizes of buttons are used with different types of garments. For example, in the case of sack coats one selected size of button is stitched to the coat front. Generally a larger sized button is attached to the coat front of an overcoat or a topcoat.

The preferred technique used in attaching the buttons is one in which each button is held by continuous loops of thread passing through the garment and holes in a button such that it is supported by a post above the surface of the garment. The post comprises the attaching loops of thread encircled by wrappings of thread which are secured against unwindings by lockings stitches passing through the wrappings and the attaching loops of thread.

Because of variance in thickness of materials to which buttons are stitched and also the requirements as to size of buttons to be stitched thereto, heretofore there has been the problem of proper location of the wrappings of the thread and locking stitches between a button and the work in order to meet the demands of the trade and purchasing public. In a properly stitched post supported button the Wrapping threads and locking stitches are located in a zone substantially midway between the underside of the button and the surface of the work. It will be appreciated that in manual stitching this requirement can be satisfied readily regardless of the size of button or thickness of the work. So also an expert tailor can control the length of the post connecting each button to the work. However, in the mechanical attachment of buttons of 3,301,097 Patented Jan. 2, 1968 varying sizes the problems of proper disposition and/or location of wrapping threads, and locking stitches, and the desired length of post which conforms to the particular size of button stitched to the work arise.

The present invention overcomes the above mentioned problems because it provides novel mechanism for obtaining the desired positioning and location of the post wrapping threads and locking stitches. It also comprises novel mechanism acting in conjunction therewith for controlling the operation of the machine in such manner that proper post length is always maintained regardless of the thickness of the material to which a selected size of button is secured.

In the embodiment of the invention disclosed herein for purposes of illustration, the machine is provided with a work-supporting table similar in construction and operation to those disclosed in the above referred to Patterson et al., Pedersen, and Johnson et al. patents, and Johnson application Ser. No. 296,039, now Patent No. 3,236,200. In accordance with the invention the work supporting table movement is so controlled that a wide range of buttons can be stitched to thin or light work and to thick or heavy work and at all times the resulting products meet and fulfill the requirements of the purchasing public. In fact, buttons stitched on machines embodying the invention so closely simulate hand stitched buttons that it is practically impossible to detect any difference, except perhaps that buttons stitched in accordance with the invention are more uniformly and firmly attached.

It is an object of the invention to provide novel mechanism for controlling the operation of the Work supporting table of a button stitching machine such that buttons of different diameters within selected size ranges can be stitched to the work.

It is a further object of the invention to provide novel selective means for adapting a button stitching machine to stitch selected ranges in size buttons to the material in order to stitch one selected size range of buttons to relatively thin work, e.g., such as sack coats and another selected size range to relatively heavy work, e.g., overcoats or topcoats.

The invention is further characterized by the provision of novel mechanism for use in a button stitching machine including means for selectively stitching relatively small buttons to light work and relatively large buttons to heavy work and wherein the length of the loops of thread connecting a button to the Work is controlled to conform with the thickness of the material or work to which it is being stitched.

With these and other objects not specifically mentioned in view, the invention consists in certain combinations and constructions which will be fully described hereinafter,

and then set forth specifically in the claims hereunto appended.

In the accompanying drawings which form a part of this specification and in which like characters of reference indicate the same or like elements:

FIGURE 1 is a side elevation of a machine provided with a preferred embodiment of the invention;

FIGURE 2 is a view taken in line 2-2 in FIGURE 1;

FIGURE 3 is a plan view, partly in section of the mechanism shown in FIGURE 1;

FIGURE 4 is a plan view of the post winding lock stitch control mechanism;

FIGURE 5 is a side elevation, partly in section, of the work support table illustrating the end play control mechanism of the work clamping carriage;

FIGURE 6 is a plan view of the same, taken on line 66 in FIGURE 5;

FIGURE 7 is a View taken on line 7-7 in FIGURE 5;

FIGURE 8 is a schematic plan view of the work support table restraining mechanism in lock-out position when a button is stitched to heavy material, and

FIGURE 8A is a schematic plan view of the work support table restraining mechanism in normal position when a button is stitched to relatively thin material.

In accordance with the invention mechanism is provided which makes it possible to adapt a button stitching machine of which it forms a part in a minimum of time from one capable of stitching one range of sizes of buttons to a machine which can stitch with equal satisfaction another range of sizes of buttons. For example, for a given run it may be desired to stitch twenty-four (24) ligne buttons, and for another run thirty (30) ligne buttons. This novel result is obtained by mechanism which controls the work supporting table motion in such manner that once a setting is made for the ranges of button sizes to be stitched, thereafter in the course of stitching operations, it is only necessary to operate a lock-out lever to secure the desired button size stitching operation.

Referring to FIGURES 1, 2, 3 and 4, the selective lockout mechanism comprises means for controlling the movement of work table T in such manner that the desired results are obtained. The selective table movement lockout mechanism includes a lock-out lever 10 pivotally mounted on stud 12, vertical plate 14 secured by screw 16 to frame member 18 of the machine. The lower edge of plate 14 is provided with spaced notches 20 (FIGURE 2) in which a stud 22 carried by lever 10 can be seated for maintaining lever 16 in a desired selected operating position when lever 10 is moved manually to the right, as shown in full lines in FIGURE 2 or to the left, as shown in dotted lines in the same figure.

The upper end of lever 10 is provided with a stepped edge portion 24, which when it is moved in the direction of the arrow L (FIGURE 2), engages an arm 26 which with a rod 28 secured thereto form a bell crank lever 30 pivotally mounted on a vertical stud 32 supported by bearing block 34 suitably secured to the frame member 18. The free end of rod 28 of bell crank lever 30 is connected through a swivel ended connecting rod 36 to cam lever 38 pivotally mounted on stud 40 in vertical bracket 42 secured to frame member 18.

Cam lever 38 pivotally supports cam follower 44 which engages with cam 46 secured to the main cam shaft 48. A tension spring 50 hooked at one end to rod 28 and anchored at the other end to the machine frame maintains cam follower 44 in engagement with cam 46.

Cam shaft 48 is rotated by means of a worm gear 52 (FIGURE 3) supported in a housing 54 integral with the framework of the machine. The worm gear drive shaft 56 extends from said housing 54 and carries a pulley 58 which through a belt 60 is driven by a pulley 62 mounted on a motor shaft 64 of a motor 66. The construction and operation of the machine drive and mechanism for effecting the desired movement of table T are essentially the same as described and shown in the above referred to Pedersen patent, and Johnson application Ser. No. 296,039, now Patent No. 3,236,200. Therefore, only such additional showing and description are given herein as is considered necessary to a full understanding of the invention.

Cams

68 and 70 also fixed to cam shaft 48 are provided for the purposes of imparting a selected longitudinal reciprocating motion to work support table T. Cam 68 is used when a two-hole button is being stitched. Cam 70 is used when a four-hole button is being stitched. Three additional cams 72, '74 and 76, also mounted on cam shaft 48, are provided for imparting selected lateral reciprocating motion through a suitable linkage to the work table T. Cam 72 is used when a two-hole button is to be stitched and cam 74 is used when a four-hole button is to be attached with a cross stitch pattern, while cam '76 is used for a four-hole button, but only when a parallel stitching pattern is desired.

The free end of arm 26 of bell crank lever 34) carries an adjustable stop stud 98.

Cams

68 and 70 are selectively engaged by cam follower 79 on cam lever 80 pivotally mounted on stud shaft 82 in bearing lug 84 of housing 54. Lever 80 is connected by a yieldingly mounted connecting rod 81 and link 83 to one arm 86 of lever 88 rockably mounted on stud 94 in the frame of the machine. The other arm 90 of lever 88 is pivotally connected to stud 92 carried by table T which is movably supported in the same general manner as that described and shown in the above referred to Pedersen Patent 3,125,046. Since this specific structure does not form a part of this invention, further description and showing are omitted in the interest of brevity. It will be understood that due to the rotation of a selected

cam

68 or 70 the desired longitudinal travel or movement of table T to and from the path of travel of the needle is effected.

Ann 86, preferably adjacent its free end, carries an inverted L-shaped stop plate 96. This plate is provided for the purpose or coaction with adjustable stop screw 98 on the free end of arm 26 of lever 30 when stud 22 on lever 18 is seated in a selected notch 20 in plate 14. As shown herein, stop screw 98 will coact with plate 96 when cam follower '79 is tracking cam 70. The action is such that when screw 98 engages plate 96 during the formation of the post wrapping and lock stitches, rearward movement of table T is prevented, and accordingly, these stitches are located properly around and in the post. That is, during this portion of the machine cycle i.e., the formation of the above mentioned stitches, the position of cam lever 38 is such that due to earn follower 44 riding on the high portion of cam 46, and arm 26 of lever 36 is located as shown in full lines in FIGURE 4. The excess motion imparted by cam 76 to lever 88, when the latter is restrained by the engagement of stop screw 98 with plate 96, is taken up by compression spring 100 which encircles connecting rod 81 and forms part of the yield-able linkage between cam lever 80 and arm 86 of lever 88.

The above described restraining action imparted to table T during post wrapping and lock stitching operation is desirable and usually employed when a smaller size button BS is to be stitched to a relatively thin material M11, as illustrated in FIGURE 8A of the drawings. However, if a larger size button BL is to be stitched to heavier material M2, as illustrated in FIGURE 8, which requires a longer post PL, the restraint mechanism is adjusted so as to adapt the machine to effect this purpose. This desired changeover is readily made by means of lock-out lever 10 which is moved by the operator from the solid line position shown in FIGURE 2 to the dotted line position, shown in the same figure. This movement of lever 10 locates stop screw 98 out of the path of plate 96 on lever arm 86 and lifts cam follower 44 above the high point of cam 46. As the result of this movement, lever 88 now can freely oscillate to the fullest extent of the motion imparted thereto by cam 70. Therefore, with this setting of lever 10, work table T is moved rearwardly a greater distance in order to locate a button with a longer post PL in proper position during the formation of the desired post wrapping stitches, and locking stitches.

Referring to FIGURES 8 and 8A it will be seen that the posts connecting button BL and button BS are of diiferent lengths. This difference in button diameter and post length is required for variations in thickness or weight of the materials to which the button is sewn or attached. A large diameter button, forty-five (45) ligne 1 /8" diameter with a correspondingly long post is required to properly fasten thick overcoat material, while a smaller diameter button, thirty (30) ligne diameter with a shorter post is required to fasten suit coats properly. Usually a larger button is more suitable for use on thick material than a small button, except in the case of thin material raincoats. In FIGURE 8 button BL is held in chuck CL at one distance from the work during the formation of the loops which attach the button to the work. In FIGURE 8A a smaller button BS is held in chuck CS a shorter distance above the work during the formation of shorter loops of thread which attach the button to the work. The chuck means which support the button are disclosed and claimed in copending Pedersen et a1. application Ser. No. 407,137, filed Oct. 28, 1964, and are not described further herein. However, the mechanism for effecting the desired operation of chucks CL and CS is essentially the same as that disclosed in Johnson et al. Patent 3,121,411 and further detailed description herein is deemed to be unnecessary since it forms no part of the present invention.

As disclosed in Johnson et al. Patent 3,121,411, following the completion of the loops of thread attaching a button to the work, the chucks CL and CS are moved to the positions shown in FIGURES 8 and 8A where the wrapping and locking stitches are formed in order to complete the attachment of the buttons to the material. In comparing the disclosures in FIGURES 8 and 8A it is to be noted that table T, when post PL is being wrapped and lock stitched, moves an additional distance D rearwardly, as shown by the two reference lines R1 and R2 in FIGURES 8 and 8A. At this time lock-out lever is in the position shown in dotted lines in FIGURE 2.

The mechanism for imparting lateral reciprocating movement to work support table T is essentially the same as that shown in copending Johnson application Ser. No. 296,039, now Patent No. 3,236,200. Since it forms no specific part of the present invention further disclosure and description thereof is omitted in the interest of brevity. Suffice it to say that lateral movement of table T is effected through adjustable connecting rod 102 having one end connected to table T and the other end secured to one arm of bell crank lever 104. The other arm of bell crank 104 pivotally connects one end of an adjustable connecting rod 106, the other end of which is connected to cam lever 108, carried by shaft 32. Lever 108 is provided with a laterally adjustable stud 107 on which is mounted a cam follower 110 (FIGURE 1), as a result of the adjustable nature of stud 107 in lever 108, cam follower 110 can be positioned as desired in conjunction with position of cam follower 79 on

cams

68 and 70 for engagement with a selected

cam

72, 74, or 76.

In order that all types of work, or materials to which buttons are to be stitched can be positioned properly with respect to the needle, and especially during the formation of the first stitch or stitches made in securing a button to the work, the invention includes novel mechanism for adjusting or changing the end play of work clamping carriage 112 (FIGURES 5, 6 and 7). By means of this mechanism the depth setting of the work clamping table 112 relative to the work supporting carriage 114 is readily adjusted in order to accommodate properly light as well as heavy materials or work to which buttons are to be stitched. Carriage 114 adjustably supports the work holding plate or tongue 116 over which work or material M to which buttons are to be stitched is folded or draped by the operator of the machine in the same manner as shown and described in Patterson et al. Patent 2,739,550.

The construction and operation of work clamping carriage 112 and work supporting carriage 114 are generally similar to corresponding structure shown and described in Pedersen Patent 3,125,046. Therefore, the description and disclosure herein is limited to such disclosure as is necessary to an understanding of the invention.

Carriage 112, which has a shoulder 119, is provided with two pairs of spaced rollers 118 which are confined to travel in tracks provided in the top portion of table member 120. A plunger 122 shown in FIGURE 6 is located in bore 125 formed in lug 126 fixed to table member 120 and extending upwardly into cavity 128 formed on the undersurface of carriage 112, as shown in FIGURE 5. Bore is formed substantially centrally in lug 126 and is located substantially centrally in carriage 112. A spring 124 which encircles plunger 122 has one end seated against the base of bore 125; its other engages the head of plunger 122 and acts thereby to maintain the head of plunger 122 in engagement with shoulder 119. In this manner work clamping member 112 normally is biased rearwardly, or to the left, as viewed in FIGURES 5 and 6.

Referring to FIGURES 5 and 6 it. will be seen that an L-shaped cam block 130 is mounted in cavity 123 in carriage 112. This block is provided with an elongated slot 132 through which extends an adjustable mounting screw 134 which permits an adjustment of cam block 130 to the right or left, as viewed in FIGURE 5. Table member 120 is provided at its forward portion (see FIGURES 5 and 7) with a suitable inclined opening 136 through which moves the free end of a generally hook-shaped cam arm 138 secured to one end of a horizontal rod or shaft 140 suitably rotatably supported in hearings in table member 120. The free end of rod 140 is located adjacent the operators side of the machine where it can be readily engaged for moving cam arm 138 into and out of operative position relative to work clamping carriage 112.

In FIGURES 5, 6 and 7, cam arm 138 is shown in its operative position, located between the rear face of the upstanding leg of cam block 130 and the front face of the rear portion of carriage 112. In FIGURE 7, cam arm 138 is shown in broken lines in its inoperative position. Due to the fact that spring 124 biases clamping carriage 112 rearwardly or to the left, as viewed in FIGURE 5, against surface 115 of carriage 114, a space 144 is created between the rear end of the cavity 128 in carriage 112 and the stationary cam block 130 mounted on table member 120, when cam arm 138 is in the dotted line position shown in FIGURE 7.

Work clamping carriage 112, when cam arm 13% is in the full line position shown in FIGURES 5, 6 and 7, will have a minimum amount of end play which will depend upon a setting of cam block 130. The position of cam block 130 can be adjusted by loosening screw 134 by means of the removal of access plate which is detachably secured to carriage 112 by screw 137. A desired adjustment of cam block 130 can be made without disassembling the work support table T.

Cam arm 138, which acts as a locking member on carriage 112, is held in its engaged operative position by means of fiat spring 139, which acts as a locking means on arm 138 and which is suitably mounted on table T and engaging one of the notches 141 formed in the cam arm lever. When cam arm 138 is moved to its inoperative position the nose of fiat spring 139 engages notch 143 and thereby maintains it in the broken line position shown in FIGURE 7.

When the operator folds the cloth or material M at the point where a button is to be stitched over the fornt end of work supporting plate or tongue 116 carried by carriage 114 and then pushes carriage 114- forwardly, the material is clamped between said tongue 116 and a tension and clamping plate 146 mounted on and carried by the work clamping carriage 1112 described heretofore. When cam arm 138 is locked in space 144, as described above, the carriage 112 cannot yield forwardly and simply imparts a clamping action upon a relatively thin material. This may be termed standard clamping condition. However, if a heavy material is used this clamping effect upon the material would be too severe and perhaps distort or damage it. For this reason, when using heavy material, cam arm 138 is moved out of space 144, as shown in dotted position in FIGURE 7, thus permitting the carriage 112 to yield forwardly against the spring plunger 122 when the heavy material folded over the tongue 116 and moved forward by the operator engages with the clamping plate 146 carried by the carriage 112, thereby preventing excessive clamping and pinching of the heavy material.

To further facilitate the handling of heavy and/ or multilayer material the machine may be provided with a relatively large, suitably shaped supplementary work supporting plate 150 (FEGURES and 6) provided with a suitable cut-out 152 to permit the protrusion of the work supporting tongue 116. Plate 150 is secured by means of a pair of spacer brackets 154 to cover plate 156 attached by screws 153 to table T. It will be apparent that work supporting plate 150 not only serves the purpose of affording the operator a larger area on which to support heavy garments to which buttons are to be stitched, but also to hold them more securely during the stitching operation. When a heavy garment is to be stitched the operator must use both hands to hold the garment firmly on supporting plate 150. She would, therefore, find it diflicult to move work support tongue 116 forwardly, or to the right, as viewed in FIGURES 5 and 6 in order to locate the free end thereof in locking engagement with clamping plate 146. For this reason a cable 160, having one end suitably attached by clamp 162 to work supporting carriage 114 which carries tongue 116 is led over a pair of

suitable pulleys

164 and 166 to a suitable treadle 168 which the operator can readily depress in order to effect the desired forward movement of carriage 114 and work supporting tongue 116.

What we claim is:

1. in a button stitching machine having a table for supporting the work and a button to be attached thereto, opposed needle bars for passing a threaded needle back and forth through selected button holes and said Work, and forming wrappings of thread about said loops of thread to produce a post connecting said button to said work, and locking stitches in said post, and mechanism for moving said table to position said work and said button relative to said needle in accordance with a predetermined stitching pattern; the combination With said table moving mechanism of means for selectively controlling said mechanism to limit the extent of movement of said table toward said needle during the formation of said locking stitches to cause said needle to be passed back and forth through said post in a position substantially equidistant between the surface of said work and the undersurface of said button, wherein said means comprises a lock-out device to restrict the travel of said table and locate said table at a predetermined position relative to said needle when a given range of button sizes is to be attached to work, including means to incapacitate said lockout device to allow full movement of said table and its positioning thereof at a different location relative to said needle when buttons of a larger range of button sizes is to be attached to said work.

2. In a button stitching machine having a table for supporting the work and a button to be attached thereto, opposed needle bars for passing a threaded needle back and forth through selected button holes and said work, and forming wrappings of thread about said loops of thread to prOduce a post connecting said button to said work, and locking stitches in said post, and mechanism for moving said table to position said work and said button relative to said needle in accordance with a predetermined stitching pattern; the combination with said table moving mechanism of means for selectively controlling said mechanism to limit the extent of movement of said table toward said needle during the formation of said locking stitches to cause said needle to be passed back and forth through said post in a position subtsantially equi-distant between the surface of said work and the under-surface of said button, wherein said control means comprises selectively operated mechanism for restricting movement of said table relative to said needle in accordance with differences in ranges in button sizes whereby said needle may be passed substantially centrally through the post of thread connecting a button to said work, and wherein said mechanism for restricting movement of said table comprises an operating arm, a plurality of cams, means for selectively coupling said arm to one of said earns, a lock-out lever and means for securing said lock-out lever in selected operating position corresponding to the size of button to be stitched, and the thickness of the work to which it is to be attached.

3. In a button stitching machine having a table for supporting the work and a button to be attached thereto, a work clamp carriage, a clamp plate on said carriage, a work supporting tongue, means movably mounting said clamp carriage and said tongue on said table for movement of said tongue supporting work to which a button is to be stitched relative to said clamp carriage and said plate, opposed needle bars for passing a threaded needle back and forth through selected button holes and said work, and forming wrappings of thread about said loops of thread to produce a post connecting said button to said work, and locking stitches in said post, and mechanism for moving said table to position said work and said button relative to said needle in accordance with a predetermined stitching pattern; the combination with said table moving mechanism of a selectively operated means coacting with said clamp carriage to limit the forward movement thereof in positioning said work on said tongue against said clamp plate adjacent the path of travel of said needle in response to the pressure of said work, including a cover plate mounted above said work supporting tongue and said table for supporting the main body of said work to which a button is to be attached.

4. In a button stitching machine having a table for supporting the work and a button to be attached thereto, a work clamp carriage, a clamp plate on said carriage, a work supporting tongue, means movably mounting said clamp carriage and said tongue on said table for movement of said tongue supporting work to which a button is to be stitched relative to said clamp carriage and said plate, opposed needle bars for passing a threaded needle back and forth through selected button holes and said work, and forming wrappings and thread about said loops of thread to produce a post connecting said button to said work, and locking stitches in said post, and mechanism for moving said table to position said work and said button relative to said needle in accordance with a predetermined stitching pattern; the combination with said table moving mechanism of a selectively operated means coacting with said clamp carriage to limit the forward movement thereof in positioning said work on said tongue against said clamp plate adjacent the path of travel of said needle in response to the pressure of said Work, wherein said selectively operated means comprises means on said tongue engaging a shoulder on said clamp carriage for advancing said clamp carriage to said operating position, a locking member positioned between said last named means and said shoulder, and manual means for moving said member between said last named means and said shoulder to prevent forward movement of said clamp carriage.

5. The invention defined in claim 4 including spring means normally biasing said clamp carriage towards said means on said tongue, and locking means for securing said locking member in its selected operating position.

References Cited UNITED STATES PATENTS 3,125,046 3/1964 Pedersen 1l21 10 3,236,200 2/1966 Johnson 112110 3,246,618 4/1966 Johnson et al. 112-110 JORDAN FRANKLIN, Primary Examiner.

G. H. KRIZMANICH, Assistant Examiner.