Patent GB-1432343-A (GB)
Title: Lawn mowers
IPC: A01D34/47
Filed: 1972-03-27
Abstract: 1432343 Gang mower machines RANSOMES SIMS & JEFFERIES Ltd 27 March 1973 [27 March 1972] 14343/72 Heading A1F [Also in Division F2] A motor driven lawn mower has an internal combustion engine 20 which drives a pair of variable delivery axial flow swash plate hydraulic pumps 22 and 24. The traction wheels 12 are driven by hydraulic motors 26 connected in parallel to pump 22 to give a differential action, and the cutting cylinders 28 are driven by motors 30 connected in series to pump 24 so that they all rotate at the same speed.  Hydraulic Circuits  Valves 34 Fig. 8 can be set to by-pass motors 30 if rotation of only selected units is required. The valve 36 can transfer pump 24 output to the traction motors 26 to supplement pump 22 during transport of the mower or valve 36 can be set to place motors 26 in a free wheel condition so that cylinder motors 30 can be rotated whilst machine is stationary (e.g. for driving in reverse for sharpening). The cutting unit lifting rams 19 are operated by a boost pump 48 through control valves 50. Pump Output Ratio Control  Rotatable control shafts 52 and 54 Fig. 3 determine rate of delivery and direction of flow of pumps 22 and 24. A main control shaft 60 is connected via lever 63, bush 66, bar 68 and rod 70 to a selector assembly (80), Fig. 5 (not shown), which is fixed by a clamp block 82 to the pump control shaft 52 so that rotation of shaft 60 effects rotation of shaft 52. Selector assembly (80) has two position settings which determine relative movement of pump control shaft 52 produced by a given angular movement of the main control shaft 60. The control shaft 54 of pump 24 is similarly connected to the main control shaft 60 and has a two position selector assembly (110) Fig. 6 (not shown), to determine relative movement. By positioning selector assemblies 80 and 110 in the desired settings the ratio of rotational speed of the cutting cylinders 28 to the traction wheels 12 can be set to give the desired cuts per yard. Machine Control Mechanism The right hand end of the main control shaft 60 is connected via sleeve 114, quadrant plate 116 and lever 118 to a pedal 120. A second control shaft 122, is connected to pedal 134 and intermeshes with control shaft 60 via pinions 124 and 126. When the two pedals are at similar longitudinal positions, the pump control shafts are in their neutral positions. When pedal 120 is pushed forward and pedal 134 comes back, the main control shaft 60 is rotated and this causes pumps 22 and 24 to supply fluid to the wheel motors 26 and cutting cylinder motors 30. The fluid supplied by the pumps and hence the speed of the motors will be in the ratio set by the selector assemblies (80) and (110) and will remain so for the full movement of the pedals 120 and 134 in either direction. A selector assembly, Fig. 4 (not shown), which can only be operated when the pedals are in the neutral position, enables the operator to make four selections (Ahead, Reverse, Neutral, Ahead and Reverse) according to the machine operation required. These selections limit pedal movement by the pin 146 on the quadrant 116 being restricted in travel according to the selected position of the shaft (138) and sleeve (136). The selector assembly also ensures by means of a cam-operated solenoid (160) that the pedals are in the neutral position for starting the machine.