Patent GB-694728-A (GB)
Title: Improvements in or relating to lift trucks
Inventor: EHMANN LESLIE GEORGE
IPC: B66F9/18
Filed: 1950-07-03
Abstract: 694,728. Lift trucks; grab buckets. HYSTER CO. July 3. 1950. No. 16529/50. Classes 78 (iii) and 78 (iv). A lift truck comprises a lift carriage, a pair of load arms mounted on opposite sides of the carriage for lateral sliding movement thereon between retracted and extended positions and a pair of horizontal fluid pressure cylinder and piston rod units disposed one above the other in overlapping relationship for moving the respective load arms between the retracted and extended positions. As shown, an upright frame 20 guides a lift frame 22 supporting a load carriage 30 having a pair of arms 31 and pairs of rollers 32, 33, 34 mounted on vertical side plates 35 to guide the load-carriage along the uprights. The carriage is raised and lowered by a link chain 38. Each arm 31 is bolted to a cross head member 44 connecting tubular slides 45 sliding in tubular guides 46 and the outer end of each pair of guides is interconnected by a plate 49. The arms are extended and retracted by horizontal cylinders 50 one end being pivotally mounted on a pin 51 extending through ears 52 on plates 49. Within each cylinder is a piston on a piston rod 54 whose outer end is pivotally connected with a pin on a pair of ears on the member 44. The rods and arms 31 are extended by pumping fluid into the cylinders 50 through a conduit 60 connecting with branch pipes 62 and flexible conduits 63 to the inner ends of cylinders. The rods and arms are retracted by pumping hydraulic fluid through a conduit 65 into the outer ends of the two cylinders. The conduits 65 have branch pipes 67 and flexible conduits 68 leading to the outer end of the cylinders. The flexible conduits 60 and 65 are trained over a pair of sheaves 69 at the top of the lift frame to accommodate vertical movements of the carriage. To control the relative movement of the two pistons a small orifice in the wall of the cylinder 50 where conduits 63 and 68 are attached restricts the flow of the oil into and out of the cylinder to maintain the working pressure regardless of the resistance encountered by the arms. The arms 31 comprise channel shaped members comprising top and bottom flanges attached to a vertical member. The arms are slightly convergent outwardly. The inner surface of the arm may have a perforated rubber pad or a spiked steel plate, alternatively, the arm may have a short inner rubber pad and at the outer end a small rotatable rubber pad which is useful for tipping or turning over. For handling drums the top and' bottom flanges of the arms are recessed in circular ares with extended narrow ends. To enable the arms to contact the ground the arms may be mounted on extension brackets. For handling fragile packages the pressure in conduit 65 may be controlled by an auxiliary valve. The lift carriage may be rotated to invert an object, the guides 46 then form an integral part of a frame having a plate rotatable on the lift carriage. The plate is supported on a hollow bearing having a central opening for the flexible tubes. The guides and slides may be of rectangular cross-section. To operate a clamshell type bucket. Fig. 16, the bucket members 105 are supported by tubular bearings 106 mounted on trunnion arms 31e carried by the cross-head 44. The upper end of each bucket member 105 is pivoted to links 108 so that moving arms 31e opens and closes the bucket.