Patent GB-497178-A (GB)
Title: Improvements in and relating to multiple lift elevating trucks
IPC: B62B3/06
Filed: 1938-01-11
Abstract: 497,178. Elevating-trucks. HUGHES, R. M. (Lewis-Shepard Co.) Jan. 11, 1938, No. 909. [Class 108 (i)] In an elevating-truck comprising a main frame I having a head 3, an upwardly movable load-supporting platform 21 carried by links 25, or toggles &c., and steering-mechanism. having a vertically swingable tongue 19, the steering-mechanism has a vertical tubular steering-post rotatably mounted in the head, and the means for raising the load include a flexible member connected to the load-supporting platform with means mounted on the head and steering-mechanism for guiding it upwardly and thence downwardly through the steering- post, and means mounted on the lower portion of the steering mechanism and selectively operable by successive vertical swinging movements of the tongue to pull the flexible member lengthwise, means also being provided for locking the load-supporting platform at each step of elevation. As shown, the head 3 is provided with a cylindrical extension 11 forming a bearing for the tubular steering-post 12 integral with a plate 13 having downwardly extending forks 14 carrying the steering-wheel 16 and provided with forward extensions 17 carrying a shaft 18 on which is mounted the forked lower end of the tongue 19. The flexible member consists of a chain having upper and lower sections 29 and 37 connected by swivelling-sleeves 35 and 36 slidable in the steering post 12. The upper section is attached at its rear end to the platform 21 and is passed over guide pulleys or sprockets 31, 33 mounted on extensions 6, 8 of the head 3 respectively. The lower section is passed over a pulley 38, mounted on the forks 14, and round a pulley 20, and is connected to a spring 40 attached to an extension 42 of one of the forks 14. When the tongue is swung downwardly, the chain is pulled lengthwise by a spring-pressed pawl 43 pivoted to the tongue. The load is locked at each step of elevation by a spring-pressed detent 60 having a hooked end 61 engaging the chain 29 and pulley 31. The detent is pivoted on a rod 63 connecting two levers 64, pivoted on the shaft 34 of the pulley 33 and having rounded rear ends engaging the extensions 6. To lower the load, the tongue is brought to a vertical position and a knob 50 connected to the pawl depressed. This disengages the pawl from the chain and engages a slot 46 in an extension 45 of the pawl with a pin 69 connecting two links 68 pivoted to the levers 64. The tongue is then swung downwardly and the levers 64 thus rotated to disengage the detent 60 from the chain, the detent being guided by a pin 72 riding on the inclined surface 71 of a plate 70 attached to the portion 8. A dashpot is provided to cushion the descent of the load. In the construction described, the smallest step of elevation possible is one corresponding to a movement of the chain of one link and in a modification, two chains in staggered relationship are used to enable the load to be raised in half-steps corresponding to movements of the chains of half a link, two detents and pawls being provided. In another modification using two chains, one pawl and one detent are used and engage with ratchets fixed between the sprockets over which the chains pass, the ratchets having twice as many teeth as the sprockets to enable the load to be raised in half-steps. Specification 499,917 is referred to.