Patent GB-505684-A (GB)
Title: Improvements in lifting mechanism for horse and tractor drawn ploughs and other agricultural implements
IPC: A01B63/24
Filed: 1937-12-29
Abstract: 505,684. Self - sustaining gear for winding - apparatus. RANSOMES, SIMS, & JEFFERIES, Ltd., and CHALLACOMBE, A. Dec. 29, 1937, No. 36002. [Class 78 (v)] [Also in Group I] Lifting-mechanism for ploughs &c. comprises chain pulleys which are retained under load by a brake which is released by a cam operated by a lever. The cam produces a gradual release of the brake before releasing it completely. In the form shown in Figs. 1 and 2 a chain pulley 1 having ratchet teeth 2 is mounted freely on' a shaft 3 carried by a bracket 4 fixed to the tractor. The pulley 1 has a boss 5 also-provided with ratchet teeth 6. The pulley is rotated to lift the plough by a lever 17 on a pivotally mounted yoke 16 which carries a pawl 18 engaging the teeth 2. The plough is retained in the lifted position by a brake drum 7 which is provided with pawls 10 engaging the teeth 6. The pawls 10 arc carried on pins 11 on a web 9 of the brake drum, the web being integral with a hub 8 mounted to rotate freely on the shaft 3 within the boss 5 of the pulley 1. A lubricating passage 15 leads to an antifriction washer 14. The drum 7 is surrounded by a band 20 pivoted at one end on a pin 21 on an arm of a lever 23 pivoted at 24 on the bracket 4. The other end of the band is fastened to an adjusting screw 22 which passes through a trunnion pin 22<1> in the lever 23. The lower arm 25 of the lever is attached to a spring 26 which keeps the brake band tight. To lift the plough the lever 17 is moved backwards and forwards causing the pawl 18 to rotate the pulley 1 which is prevented from moving backwards during the return stroke of the lever 17 by the pawls 10 of the brake drum. To lower the plough the lever 17 is moved beyond its normal stroke so that the pawl 18 strikes a trip 29 and is thereby released from the teeth 2. A cam 19 on the lever 17 then strikes a roller 27 on the lever 23 which is thus rocked to loosen the brake band. The cam 19 is shaped to produce a gradual release of the brake before completely releasing it. The lifting chain 27<1> may be attached directly to the tool frame to be lifted or it may be secured to a segment 30, as shown in Fig. 4, fast on a shaft 31 which carries other segments 32 having chains 33 attached to the tool frame 34. Fig. 5 shows a modification in which power for lifting the tools is obtained from the land wheels of the implement. The lifting pulleys are fixed to the shaft 3 on which the band brake drum 7 is loosely mounted, a ratchet wheel 43 fixed on the shaft being engaged by a pawl 41 carried by the drum 7. One end of the brake band 20 is hinged to a pin on a lever 23 attached to a spring 26, the lever being raised to release the brake by a lever 17 having a cam 19 which engages the lever 23. The shaft 3 is rotated by a rack 35 pivoted at its rear end to levers or cranks fixed to the shaft 3. The rack is normally held out of engagement with pins 38 on a wheel 39 fast with the land wheel by a weight 40. To raise the, tools the rack is depressed into engagement with the pins 38 by a lever 42. To ensure that the lever 17 is in the brake-on position before the rack 35 is disengaged from the pins 38 an arm 431 pivoted at 44 to a crank on the shaft 3 is provided with a cam surface 47 and rests on a fixed bar 46. While the rack 35 is in engagement with the pins 38 the arm 43<1> moves forward and if the lever 17 has not been moved to the brake-on position the arm 43<1> will abut against the lever and move it to the brake-on position. When the rack 35 has moved to the end of its travel the cam 47 rides over the bar 46 and the arm 43<1> is released from the lever 17 which can then be moved to release the brake.