GB630168A - Lift truck - Google Patents

Abstract

630,168. Hoisting - apparatus YALE & TOWNE MANUFACTURING CO. May 19, 1947, No. 13441. Convention date, Aug. 15, 1946. [Class 78 (iii)] An industrial truck in which a load carriage is supported for lifting and lowering movement upon a set of secondary uprights which in turn are mounted for lifting and lowering movements upon a set of primary uprights has one hydraulic ram connected to the load carriage for raising the carriage relatively to the secondary uprights and a second hydraulic ram connected to the secondary uprights for raising the uprights relatively to the primary uprights. As shown, the truck operated from a battery has a load elevating carriage 10, movable on a pair of secondary uprights 11, which are mounted on and are movable on a pair of primary uprights 12. The carriage 10 is secured to a member 27 fitted with rollers 28, 29 adapted to move vertically in the channel 30 of the secondary uprights 11. The secondary uprights are secured to a carrying member 31 having rollers 32, 33 moving vertically in channels 34 of uprights 12. The primary uprights are mounted to tilt on stub shafts 35 under the action of a ram 36 having a piston connected between standard 20 and the primary uprights. The carriage 10 is moved relatively to the secondary uprights 11 by a ram 46 pivotally supported at 47 on the secondary uprights and operating through a pair of chains one end of which is secured to the carriage 10 and the other end to the secondary uprights 11. The secondary uprights and carriage 10 are similarly lifted relatively to the primary uprights 12 by a ram 55 pivoted at 47a to the uprights 12. The rams 46 and 55 receive fluid from a pipe 65 and fluid flows first to the ram 46 to lift the lighter load first, which is the carriage 10, and then to the ram 55 to lift the secondary uprights and carriage. To lift the load, the operating handle 18 connected to a control rod 22 is moved to the left, closing valve 112 electrical contact is made at 108 and the electric motor 23 is started and the pumps 25, 26 drive fluid through pipe 113 lifting ball valve 115 and passing along pipes 116, 117, 118, 119, of the valve regulator device 95 through bore 120 and speed control passage 98a and of piston 96 and into pipe 65 to ram 46 lifting the carriage 10 and then into ram 55 lifting the secondary uprights. Simultaneously fluid flows from the reservoir R into pump 25 and through pipe 121 into passage 122 of control valve T into passage 133 and through bore 71a of spool 71 about a stem 72 of rod 21 and into chamber 70 thence through passage 70a and into pipe 123 into pipe 113 and joins the output of the first pump 26. To hold the load in any elevated position the rod 22 is moved to the right, Fig. 8, fluid then cannot flow past ball valve 115. To lower the load, the rod 22 is moved to the right pin 124 unseats ball 102 the pressure in chambers 126, 99 tend to equalise, valve 105 is moved to the right and fluid flows to chamber 126. This allows fluid to flow from pipe 65 via port 125 into chamber 126 and through pipe 128 to reservoir R. To tilt the load, the control rod 21 is moved by a handle 17 in the direction according to tilt. When the rod is moved to the right, groove 130 of spool 71 is aligned with bore 129 closing circuit at switch 93 and motor 23 is actuated to operate both pumps. Fluid from pump 26 moves through pipe 113, bore 112, chamber 126, and pipe 128 back to reservoir R. Fluid from pipe 25 will flow through pipe 121, bore 122, bore 129, groove 130 into chamber 78 past ball valve 82 and regulator valve 84 into pipes 131 and then into ram 36 against piston 37 to tilt the load. Simultaneously fluid will flow from the other side of piston 37 through pipe 132 into regulator valve 84, ball chamber 81 is unseated the fluid flows into chamber 78 through bore 133 and bore 71a into chamber 70 into pipe 123 joining the output of pump 26. Lifting and tilting may be effected at the same time.