Patent GB-651215-A (GB)
Title: Improvements in or relating to industrial trucks
IPC: B66F9/19
Filed: 1948-01-01
Abstract: 651,215. Fork trucks ; load-engaging devices. CLARK EQUIPMENT CO. Jan. 1, 1948, Nos. 45 and 48. Convention dates, Jan. 3, 1947 and Aug. 6, 1947. [Classes 78 (iii) and 78 (iv)] An industrial truck carries a load-supporting carriage 14 mounted by means of rollers 15 for movement along upright channel-section guides 13 telescoping within channel-section guides 12 which are mounted near their lower ends for tilting movement, the carriage 14 being raised and lowered by cable means operated by a hydraulic cylinder connected between the guides 12 and 13. A pusher rack 32 is mounted by means of channel section guides 30 running on rollers 70, 72 secured to the load carriage 14 for movement over the forwardly extending load-supporting plate members 25 of the carriage 14 and is provided with a load-engaging clamp by means of which it may draw a sheet-like pallet supporting a load on to the plates 25. As shown from the rear of the rack 32 in Fig. 3, the clamp comprises a blade 53 mounted for vertical movement between guides 54, 55 on the rack 32 and biassed upwardly by springs 58, but adapted to be pressed into engagement with a fixed surface 40 by hydraulic rams 47 which also serve to retract the blade 53. To ensure an effective clamping action on the pallet the surface 40 is formed with a groove 56 (Fig. 1), into which the end of the pallet is pressed by the blade 53. The inclination of the guides 30 may be adjusted by moving a bracket 73, on which the rollers 70, 72 are mounted, about an axis coinciding with that of the roller 72. The rack 32 is further guided by a roller 114 (Fig. 3), engaging in a slot between the plates 25. The rack 32 is moved on its guides by hydraulic rams 87 (Fig. 1), automatically controlled in conjunction with the rams 47 in such a way that the clamping blade 53 is raised immediately before the rack moves forwardly and lowered immediately before the rack moves rearwardly. Each ram 87 comprises a cylinder secured at 86 (Figs. 1 and 7), to the bracket 73 and provided with connections 105, 89 for admission or exhaustion of pressure fluid. Within the cylinder slides a piston 95 carrying a hollow piston rod 62 sliding in a gland 88 and secured at 60 (see also Fig. 3), to the rack 32. A port 97 connects the pressure fluid connection 89 through the hollow piston 62 to a passage 98 connected by a conduit 63 (Fig. 3), to one side of the piston of one of the rams 47 while a tube 108 passing through the piston 62 connects the conduit 105 to a connection 109 to a conduit 66 connected to the other side of the piston of the ram 47. The passages 89 of the two rams 87 and the conduits 105 are controlled by a valve so that fluid may be admitted to either side of the pistons 95 and exhausted from the other side, a flow divider mounted on the carriage being connected in the circuit ensuring that the same volume of fluid flows to each ram. When pressure fluid is admitted through the conduits 105 pressure cannot build up to move the rack 32 outwardly to push a load off the plates 25 until the rams 47 have operated to raise the blade 53, and similarly the rack 32 cannot be moved rearwardly until the rams 47 have lowered the blade 53 to clamp a pallet. A transverse plate (not shown) bolted to the carriage 14 carries supports 29 for the guides 30 and frame members 27 to which are pivoted the brackets 73 carrying the rollers 70, 72 and also the cylinders 87 ; thus, the transverse plate may be removed together with the rack 32, cylinders 87 and guides 30. A further plate 23 carrying the plates 25 is also bolted to the carriage.