US2604220A

US2604220A - Grab mechanism for industrial trucks

Info

Publication number: US2604220A
Application number: US83488A
Authority: US
Inventors: Joseph A Frischmann
Original assignee: Towmotor Corp
Current assignee: Caterpillar Industrial Inc
Priority date: 1949-03-25
Filing date: 1949-03-25
Publication date: 1952-07-22
Anticipated expiration: 1969-07-22

Description

July 229 1&2 J. A. FRHSQHMANN GRAB MECHANISM FOR INDUSTRIAL TRUCKS 5 Sheeis==5heet 1 Filed March 25,, 1949 IN V EN TOR. 40551 A FE/JCHMANN TOE/YE K5 y 9 E952 J. A. FRESQHMANN zgfim zm GRAB MECHANISM FOR INDUSTRIAL TRUCKS I Filed March 25., 1949 35 shee'ts lhee't 2 IN V EN TOR. I JOSEPH A. FRASCH/VIANN BY M JEHHSY 1192 J. A. FRHSCHMANN 2fi422 GRAB MECHANISM FOR INDUSTRIAL TRUCKS Fileci March 25,, 1949 3 Sheets-Sheet 5 L I N V EN TOR. j JOJZPf/A imam/244m BY 7/ Y M 147 Eli/[V5 Patented July 22, 1 952 GRAB MECHANISM FOR. INDUSTRIAL TRUCKS Joseph A. Frischmann, Cleveland, Ohio, assignor to Towmotor Corporation, Cleveland, Ohio, a

corporation of Ohio Application March 25, 1949,'Serial No. 83,488

3 Claims. 1

This invention relates to industrial lift trucks and is particularly directed to mechanism for improving the performance and extending the utility of such trucks in connection with the handling of drums, paperrolls, boxes, barrels, and other articles which may be gripped for lifting.

The most common manner of handling loads with lift trucks involves the utilization of pallets or skids which comprise, generally, a load-supporting platform mounted in spaced relation with the floor to accommodate the entry of the forks associated with the load-elevating mechanism. This system is not particularly well adapted to some types of loads and is obviously disadvantageous in loading freight cars or vans since, in such cases, the pallets must be forwarded with the merchandise, and must, therefore, be sacrificed or must be returned at considerable, cost. Supporting the load by pallets is also unsuited to conditions in which it is desired to up-end or invert the load.

It has also been the practice to utilize a plate or blade organized for insertion beneath an article, such as a roll of paper, incident the elevation thereof. Such device,- however, required the exercise of extreme care and skill of operation in order to avoid mutilation or damage to the load.

The present invention contemplates a pair of jaws arranged to seize, lift, and sustain a load during transportation thereof without the use of a pallet or. platform of the character referred to above. The invention further contemplates mechanism for the rotation of the article bein handled about a horizontal axis so that it may be up-ended, inverted, or laid on its side- The preferred embodiment of the invention comprises a novel carriage adapted for use with a lift truck of conventional form by incorporating the improved gripping, rotating, and elevating structure therein. The invention further comprehends an improved gripping jaw and an improved hydraulic system for operating the jaws in all positions and under all conditions of rotation thereof. The improved gripping mechanism is particularly adapted for use with a rotatable carriage since the means for effecting the transmission of oil to the jaw-operating mechanisms does not limit or impede the rotation of the carriage.

Another feature of the invention resides in the provision of an improved roll-over mechanism.

A stillfurther feature ofthe invention which 2 v contributes to its successful operation of the machine resides in the incorporation of the improved grab arm mechanism which is designed to assure adequate surface contact with the load and is inherently adaptable to loads of various sizes and shapes.

Another advantageous feature of the invention resides in arranging the parts of the grab mechanism to accommodate the quick and easy removal of the arms so that the conventional forks may be readily installed, thus increasing the operative range and utility of the machine.

The invention also may incorporate an improved hydraulic system which is eifective to maintain the gripping engagement of the grab arms with the object being lifted. These fea-' tures of the hydraulic system are disclosed in my copending application Serial No. 60,726, filed November 18., 1948, now Pat. No. 2,596,895, entitled Article Gripping System for Lift Trucks.

The principal object of the invention is to PI'O! vide an improved article-handling system for lift trucks.

Subsidiary objects of the invention are to provide an improved grab mechanism and an improved roll-over mechanism.

The preferred manner in which the stated objects are achieved, as well as other objects of the invention more or less ancillary in nature, will be apparent to those skilled in the art from the description herein of the preferred embodiment of the invention. I

Referring to the drawings: 1

Fig. 1 is a side elevation view, with certain parts in vertical section, of the carriage of the invention shown mounted on a fragmentary portion'of a conventional lift truck;

Fig. 2 isa front elevation of the carriage wit certain parts omitted;

Fig. 3 is a plan view of the carriage and grab arm mechanism with certain of the parts thereof shown in section;

Fig. 4 is'an enlarged plan viewof the outer portion of one of the grab arms;

Fig.v ;5 is a vertical section taken on the plane truck comprising a body l2 and front wheels i3, the mast being supported by hooks l4 resting on a cross frame member l5 of the truck. Inasmuch as this structure is well-known to those skilled in the art, it need not be described in further detail herein. The device comprises a non-rotating carriage assembly indicated generally as 29 fitted with rollers I! which engage the inner walls of channel sections constituting the mast. The carriage is coupled by. conventional means (not shown) to a hydraulic cylinder I8 by which it is raised and lowered on the mast.

In general, the carriage 26, hereinafter referred to as the lift carriage to distinguish it from the rotating carriage which is mounted thereon, comprises a rigid rectangular frame fabricated from appropriate plates and bars of structural steel. The parts of this assembly include a pair of side members 2| which extend rearwardly of the carriage to support the rollers l1 and are joined at the top of the carriage by a cross frame member 22. The upright side members 2| are united by two horizontal tie bars 23 and 24. A rectangular plate 26 formed with a central opening Z'Iextends across the front of the side members 2| and is Welded thereto. Reinforcing bars 28 and a hub ring 29 are welded to the rearward face of the plate 25 concentric with the opening 21. The tie bars or cross members 23 and 24 are welded to the

members

26, 28, and 29 to form a unitary and rigid assembly. The revolving carriagelassembly indicated generally as 40 is supportedon the lift carriage by a pin 3| (Figs. 1 and 6) which is machined for rumiing clearance within the ring 29 and formed with a flange thereon which abuts the ring and is Welded thereto for the retention thereof. As shown most clearly in Fig. 6, the revolving carriage comprises a cylindrical hub 33 which is rotatably mounted on the pin 3| through

anti-friction bearings

34 and 35 disposed respectively in the inner and outer ends of the hub. Thebearings and 35 in the hub 33 are seated against shoulders in the pin in the customary manner, and the hub is retained on the pin by

snap rings

36 and 31 seated respectively in grooves in the hub and pin. A cap 30 retained.

by cap screws closes the front of the hub 33.

A disk 38 is Welded to the hub 33 .and to a pair of cross members 39 and 4| of the rotary carriage. The vertical side rails 42 of the rotary carriage are welded to the cross members 39 and 4| and are also connected to an upper frame member 43. A sprocket concentric with the hub is secured to the disk 38 by bolts 46.

The sprocket 44 is driven to rotate the carriage 40 on the pin 3| by a motor and gear box assembly, identified generally as 59, mounted on the elevating carriage. The motor and gear box are preferably similar to that disclosed in the application of William T. Wright for Industrial Truck, Serial No. 705,444, filed October 24, 1946, now abandoned. The power drive assembly 50 comprises the gear box 5| with a continuously rotatable hydraulic motor 52 mounted thereon which may, for example, be of the gear type. The motor 52 is coupled by suitable reduction gearing (not shown) in the box 5| to a chain-drive sprocket 53 which is coupled to the sprocket 44 by by an endless chain 54. (Preferably, the motor 52 drives the sprocket 53 through irreversible gearing which may comprise a worm on the shaft of the motor 52 engaged with a worm wheel which drives the sprocket 53.) The gear box 5| is supported between the vertical frame members 2| by lateral flanges 56 having elongated openings 7 therein for the reception of bolts 5'|--engaged in brackets 58 welded to the members 2|. The vertical movement secured through this structure is provided to adjust the tension of the chain 54 in compensation for elongation thereof. The adjustment is maintained by jack screws 59 (Fig. 1) bearing against the lower surface of the gear case 5| and threaded into lugs in the upper surface of the plate 26.

The rotary carriage 40 is preferably constructed to accommodate the support of various loadcarrying mechanisms; hence the grab mechanism 60 is mounted on hanger straps 6| supported by rods 62 which are retained in any suitable manner in bores 63 in the frame members 42. The grab mechanism is aligned transversely upon the carriage by spacer sleeves 64 on the rods 62. A channel iron 66 constituting a frame member for the grab mechanism is welded to the hangers 6| adjacent the lower ends thereof. The operative parts of the grab mechanism are supported on this channel and include two pivoted grab arms 19 and II (best shown in Fig. 3), a hydraulic cylinder 12 for actuation thereof, operating linkage between the cylinder and the arms, and a holding valve 15 (Figs. 1 and 2). The structure and function of the valve are described in detail in my copending application Serial No. 60,726 and now Patent No. 2,596,895 granted May 13, 1952. The arm 10 is preferably of rectangular transverse section and is provided with verticallydisposed tubes 16, H, and 18 constituting journal;

bearings for the arm and shoe assemblies. The pivot bearing 16 is mounted in the center of the arm and the bearings 11 and 18 are disposed adjacent the inner and outer ends thereof.

provided with an additional bearing intermediate the center and inner sleeves. The arm is pivoted adjacentits center upon a pin 86 which is supported in a pair of spaced

angle irons

81 and 88 fixed to the channel 66 and extending forwardlytherefrom. A second grab shoe assembly is pivoted upon the outer end of arm H by a pin 84 and the opposed end of the tie rod 8| is coupled through a clevis and pin 9| to the arm U adjacent the inner end thereof. A pin 92 in the inner end of the arm H is coupled for pivotal movement to thehydraulic cylinder 12. Thepin 92 extends through a yoke 93 mounted for'adjustment in the end of the piston rod 94 of the cylinder 12. The inner end of the cylinder 12 is formed with a trunnion 96 pivoted by the pin 91 in lugs welded to the channel member 66. As will be apparent, outward movement of the piston rod 94 will rotate the arm H and draw the grab shoe assembly 83 toward the medial axis of the truck, and the tie rod 8| will effect a like movement of the arm 19 as shown by dotted lines in Fig. 3. The proportions of the parts are such thatthe amount of movement of the outer ends of the two arms is substantially equal. Retraction of the piston rod 94 to open the grab arms 70 and H is effected by the introduction of pressure fluid into the opposite end of the cylinder.

Hydraulic fluid for actuation of the motor 52 and cylinder 72 may be supplied under the controlof the operator through any conventional organization of hydraulic pumps and control valves The inner end of the arm is fulcrumed on a pin 19- and thefluid may be conducted through flexible conduits from a reservoir supported onthe frame of the lift truck to the carriage 20.- It should be understood that the motor 52 and cylinder I2 are separately and independently controlled.

The two fluid lines to the cylinder 12 are coupled with the pin 3I and hub 33 of the revolving carriage as shown most clearly in Fig. 6. The

pin is drilled from the inner end thereof to form two longitudinal passageways IM and I02'which terminate adjacent the outer bearing. The inner ends of the drilled openings are tapped for the reception of pipe fittings I03 (Fig. l) for connection of the flexible hose lines I04 communicating with the motor 52. Thepassages IOI and I02 are in fluid communication with a pair of radial passages I05 and I06 disposed in spaced relation with eachother and extending to the outer surface of the pin for communication with annular grooves Ill-I and I08 :in the bore of thehub 33. Theagrooves or passageways I01 and I08 are sealed by O-rings IBI, I62, and I63. Thehub'is machined with a blind hole defining a passage I09 and a radial opening IIO communicating therewith and with the groove I08. The outer ends of the passage and opening I ID are tapped and plugged. -The hub is further-machined with a second radial opening communicating with the passage I09, the outer end of the, opening being tapped to receive.a, fltting I I2 for the connection of a flexible hose I I3 communicating with the holding valve 15. The hub is further machined with a radial opening II therein which communicates with-the hole. The-passage I09 and openings H and I I I thus provide a fluid conduit between the groove I08 and the hose I I3. Inlike manner the groove I0! is in fluid communication with an opening having a fitting I I4 therein '(Fig. 2) for the connection of a hose II communicating with the holding valve I5. These conduits, through which pressure fluid is supplied to the cylinder I2, are coupled to the holding valve I5 through conventional quick-detachable couplings I IS. The holding valve I5 is coupled through flexible conduits Ill and H8 to the cylinder 12.

From the foregoing it will be apparent that the flexible hose lines I04 are in constant fluid communication with the cylinder I2 through the passages in the pin 3I and the hub 33, the hose H3 and H5 and the hose Ill and H8, and that this communication is maintained regardless of the movement of the rotary carriage.

The holding valve I5 includes an accumulator I20 (Fig. 2) which is supplied with oil when the piston cylinder assembly I2 is operated to close the grab arms 83. The oil in the accumulator is fed into the cylinder I2 to balance any escape of oil therefrom. In addition, the holding valve I5 includes a check valve mechanism to prevent leakage from the cylinder through the manual control valve on the truck. The valve I5 further includes mechanism for opening the check valve when the control valve is operated to open the grab arms. The holding valve is mounted on a plate or'bracket B0 welded to the channel 66. In view of the full description of this hydraulic system in my aforesaid copending application, no further description thereof will be included herein.

The preferred load-engaging mechanism comprises a jaw mounted for pivotal movement on each arm, each jaw supporting two pivotallymounted load-engaging pads illustrated in Figs. 1, 3, 4, and 5, but omitted from Fig. 2 in the interest of clarity. In detail, the pivot pins 84 on the arms :10 and "II .support a jaw I3I comprising upper and lower plates I32 .and I33 united by a side plate I35. Each jaw is provided with two spaced load-engaging shoes, each of which comprises an arcuate plate I34 having a pair of. spaced lugs I36 welded to the convex face thereof. The lugs straddle the plates I32 and I33 and are linedrilled therewith for the reception of pivot pins I31. Each shoe is provided with a compressible facing pad I38 of rubber or a similar material held in place by machine screws I39. As shown in Fig. 3, the articulated jaws and shoes facilitate the rocking movement of these members to accommodate the engagement thereof with articles of different size and/or irregular configuration. For example, as shown in Fig. 3, the device is adapted to grab, without marring, cylindrical objects having 'a ratio of about two to one in diameter.

V In order to maintain the stability of. the assemblies as the truck approaches the load, the jaws and shoes are equipped with springs acting impositively to retain the outer ends thereof in an open position; that is, to swing the leading ends of the jaws and shoes away from the medial axis of the truck. The jaw I32 is urged to its open position by a helical spring I4I secured in a block I42 on the grab arm and hooked around the pivot pin I31 for the inner shoe. Outward swinging movement of the jaw is restrained by engagement of a block I43 welded to the jaw and a block I44 welded to the side wall of the tube or sleeve I8.

The shoes are biased toward their open position by a spring I46 engaged in an opening I41 in the lug I36 of the outer shoe and in an opening I48 in the lug of the inner shoe. It will be noted that these openings are so located with respect to the axes of rotation of the shoes that the spring will urge the outer ends of the shoes outwardly. The springs are designed to afford sufllcient tension to actuate the jaws and shoes but are too light to materially oppose the adjustment thereof.

The tie rod BI is bent inwardly as indicated at I5I in Fig. 3 to provide a greater clearance between the arm and the jaws and thus accommodate loads of relatively large diameter.

As will be seen in Fig. 2, the lower ends of the hangers 6I are secured to the bottom cross rail 39 of the rotating carriage by U-bolts I64 mounted in holes I65 in the rail. Since the lift forks are customarily mounted on the hangers 6| in a similar manner, the cross rail 39 is drilled to provide a series of holes I65 disposed to accommodate the desired spacing of the forks.

When the forks are substituted for the grab arm mechanism, it is only necessary to remove bolts I64, withdraw the rods 62, and disconnect the couplings II6.

A sheet metal guard I6I (Fig. 1) may be provided on the upper portion of the carriage to enclose the chain sprockets for rotating the carriage.

When it is desired to transport a load, the jaws are opened by operation of the cylinder 12 and the truck is then advanced until the jaws are positioned in juxtaposition with the central portion of the opposed sides of the load. After the cylinder is energized to close the jaws, the load may be elevated in the customary manner by raising the carriage 20. The truck may then be moved to any desired point, and the load lowered to the floor or elevated to any desired level within the range of the machine. The holding device'15 maintains hydraulic pressure in the cylinder 12 and insures the; stability of the grip, on the-article being carried.- irrespective of vibrati-onsresulting. from movement ofthe truck, which ordinarily tend to loosen the grip of: the clamping. arms.

If'itis desired to up endtheaarticle the motor 52 maybe energized to rotate vthecarria'geto any desired extent... This feature'of the machine may be utilized to invert the load or to dump containers holding scrap, waste, or raw materials. It is also possibleto lay an articleon its side or on a pallet, dock, or. other elevated support: In this connection,.it will benoted' that the offset location of the jaws with respectto the center of rotation of the rotarycarriagemakes it possible to grab a roller: drum adjacent the base thereof, or, if. desired,.at ahigher point if the carriage .is inverted; Obviously, theipoint of engagement of the grab arm may also be altered by manipulation of the elevatin mechanism for the carriage.

Although the. foregoing description is necese sarily of a detailed character, in order that the inventionmay be completely set forth, it' is to be understood that the specific terminology is not intended tobe restrictive or confining, and that various rearrangementsof parts and'modifications, of detail may be. resorted to without departing from thev scope? or spirit of the invention as herein claimed.

I claim:

1. In a lift truck, a mast, a carriage slidablealon said mast, a frame mounted on said carriage'for rotation about a horizontal axis, a cross rod detachably. mountedacross an upper part of said frame, spaced straps pivotally depending from said cross rod, a pair'of clamp jaws, means mounting said jaws on said straps, and means to restrain said straps from pivotal motion about said-cross rod.

2. Ina lift truck, a mast, a carriage slidable along said mast, a frame, pin and journal means mounting said frame on said carriage for rotation about oi-horizontal axis, fluid. passageways in said pin: and journal means, a cross rod detachably mounted across an upper part of said frame;- spaced straps. pivotally depending from said orossJrod 'a pair of damp jaws, means mounting-.saidjaws on. said straps, a piston and cylinder. assembly foraoperating: at least one of said jaws, -means. to. restrain said straps from pivotal ..motion aboutsaid cross rod, and quick attachable hoseconnections between said pin and'journal means and. said cylinder.

. 3'. Alift truck'comprising. amast, acarriage elevatableon themast, a frame mounted. on the carriage for rotation about av generally horizontal axis, a bracket-projecting forwardly from onersideof'said. frame, axfirst clamp arm pivoted intermediate: itsend on' said bracket, a"- second clamp arm pivoted adjacent its inner end at the other sideofsaid frame, a tie' rod pivoted toan inner'endv portion. of; said first arm and to an.

intermediate portion of said second arm, and a pistonand. cylinder assembly pivoted at one end to saidframe andiat the other end to the inner end of. said first arm.

. JOSEPH A. FRISCHMANN.

REFERENCES. CITED The following references are of record in the file of this patent: