Patent GB-1012561-A (GB)
Title: Improvements in or relating to suspension systems for vehicles
IPC: B62D55/112
Filed: 1961-12-29
Abstract: 1,012,561. Vehicle suspensions; endless track vehicles. INTERNATIONAL HARVESTER CO. Dec: 29, 1961 [Aug. 7, 1961], No. 46606/61. Headings B7D and B7H. [Also in Division F2] Means are provided in a vehicle, e.g. an earth working vehicle of the crawler tractortype, having at least forwardly and rearwardlydisposed sets of laterally spaced wheels independently movable in relation to the body of the vehicle, comprising means selectively operable to provide " spring " suspension for the forwardly and rearwardly disposed sets. The vehicle comprises a body having a rear portion 20 in which are located the engine 19, the various controls 21 and driver's seat and a scraper bowl 25 having an ejector plate 28 operated by a hydraulic ram 29. The body is supported on each side by links 11 upon wheels 3, 4, 5 and 6 surrounded by endless tracks 9. An apron 16 is pivotally. mounted on arms 46 and may be raised and lowered by rams 48. In the lowered position, when the vehicle works as a dozer, the lower pivoted portion 78 of the aprons 16, carrying a dozer blade 100, may be locked against rotation relatively to the upper portion 79 which may be locked to the side members of the vehicle to withstand shock. When not working as a dozer, the lower portion 78 may be locked against the upper portion 79 of the apron 16 by catches 101. The vehicle is provided with scarifying teeth 110, for the operation of which, the attitude of the vehicle will be altered and the vehicle will travel in reverse. The apron may be positioned to facilitate loading of the space 25. The floor 17 of the scraper bowl is provided with a cutting edge 37 extending over substantially the whole width of the vehicle. The wheels 3, 4, 5 and 6 on each side of the vehicle are mounted upon links 11, the links 11 of the front wheels 3 and 4 being attached to shafts 142 rigid with rotor vanes 228 of a wheel suspension unit 147 and the links 11 of the rear wheels 5 and 6 being provided with similar units 147 or being connected by bellcrank levers 234 with hydraulic rams 233, Fig. 5. The hydraulic suspension units 147 of each wheel are [connected in a hydraulic circuit, Fig. 2, incorporating a valve 148 associated with each wheel and being capable of connecting the units to the main circuit, or of connecting each wheel unit to hydraulic accumulators 152. The valves 148 associated with each pair of wheels 3, 4, 5 and 6 are interconnected, and the accumulators 152 of the wheel pairs 3 and 4 are interconnected as also are the accumulators 152 of the wheel pairs 5 and 6. Each wheel 3 and 4 is associated with two accumulators 152. Non-return damper valves 222 are provided in the accumulator circuits. The front wheel pairs 3 and 4 and the right-hand wheels 5 and 6 are also associated with levelling valves 149, 150 and 151 respectively, the circuits of which include non- return damper valves 220, 220a and 220b respectively. The hydraulic circuit comprises a pump 155 drawing fluid from a reservoir 170 and delivering through lines 171, 171a which include pressure relief valves 173, 173a and check valves 175, 175a, a line 177 from the valves 175,175a leading to a pressure regulator 156 connected with pressure accumulators 156a and 156b. The pressure regulator, Fig. 7, comprises the inlet line 177, outlet line 162 and an outlet line to the pressure accumulators 156a and 156b, each of which comprising a free piston 194 acting against nitrogen in the closed end of the cylinder. Fluid enters into chamber 180 of the regulator and unseats a non-return valve 184 and at the same time acts on one side of a free piston 187 through a passage 186. A passage 189 is provided through a spring- loaded valve 182 and acts against the other side of piston 187. If pressure in the circuit 162 builds up, the piston 187 moves to the left to unseat a spring-loaded valve 192 and liquid flows through a passage 196 and line 179a back to reservoir. Should the pressure in the line 162 fall, the valve 192 will reseat and the pressure in the accumulators will again build up. The delivery line 162 from the pressure regulator 156 is directed to a two-position valve 157, Fig. 7, and to a circuit 163 leading to the levelling valves 149, 150, 151 which are located in the front wheels 3 on each side and in the wheel 6 on the right-hand side of the vehicle. The valve 157 is connected to the reservoir and to circuits 164a, 164b which are connected to valves 148 (Figs. 2 and 5), which control the flow of fluid between the wheel suspension unit and pressure accumulators 152 and which, being similarly to the accumulators 156, may act as hydropneumatic suspension springs. In the case of wheels 3 on each side and 5 on one side only, the valves 148 are also connected to the levelling valves, each of which comprises a cam 215a, Fig. 8, rigid with the associated wheel support shaft 142 and co-operating with plungers 213 and 214 of valve elements which are inserted between the lines 163 and 217 and between lines 218 and 219. The wheel suspension units 147 when associated with a levelling valve are connected, as shown in Fig. 5 through a check damper valve 220 and pressure accumulator 152, and with a damper valve 222. The hydraulic suspension circuit is governed by valve 157 having two positions referred to as the " sprung " and " unsprung " positions. In the " sprung" position, as shown in Figs. 5 and 7, the plunger 148a of each control valve 148 is forced by fluid pressure to the right and each wheel suspension unit 147 is placed in communication with the pneumatic reservoirs 152, the valves 222 acting as flow dampers. If load is applied to or removed from the vehicle, causing the shafts 142 of the suspension links 11 to rotate, the cams 215a of the levelling valves rotate to operate one or other of the plungers 213 or 214 and so an appropriate correction is made to the loading of the suspension units 147 associated therewith, as shown in Fig. 2. A pressure relief valve 227 is included in the supply line to the wheel units 147. In the " unsprung " position, units 147 of wheels 5 discharge to reservoir through lines 244 while those of wheels 6 lock with each other through line 245, and the wheels 3 and 4 are correspondingly interlocked. The attitude of the vehicle may be controlled by raising or lowering the front of the vehicle by operating either or both of the valves 148 associated with wheels 3. The pump 155 supplies fluid to tilt control valves 158 and 159 through lines 237, 237a and non-return valves 240 (Fig. 6) and thence to the valves 148 of wheels 3 through lines 235, 235a, the control valve 157 being put in the " unsprung " position. When the spool 239 of valve 158 or 159 is put in the extreme left position to raise the associated wheel suspension unit, a pilot line 176 or 176a leading from valve 175 or 175a is blocked causing a build-up of pressure in that valve cutting off its supply to the pressure regulator 156. Upon release the spool 239 is recentred by spring 242 and pilot line 176 or 176a or both are re-opened to reservoir. The lowering operation is performed by moving valve 158 or 159 to the right, so terminating flow from pump and opening lines 235, 235a to reservoir. The placing of valve 157 to " unsprung " position allows suspension units 147 of wheels 5 to discharge to reservoir and since units 147 of wheels 6 lock with each other, tilting of the vehicle takes place about these wheels. The valves 158 and 159 are interconnected by a metering unit 160<SP>1</SP> to maintain even flow in the lines 235 and 235a when operated. The double acting rams 48 and 49 raising and lowering apron 16 are controlled by valve 161, liquid being supplied through lines 166 and 167 and chamber 253 of valve 158 and are independent of the position of valve 157. Pilot line 176 is blocked when the spool 161b of valve 161 is placed in either the raise or lower position to cause the appropriate pressure build up and liquid being supplied to one or other side of the ram through lines 254 or 254a. The ejector ram 29 is double-acting and is supplied with fluid through the lines 259 or 260 from valve 160 which has a connection to the supply line 237 through line 256 in the housing of valves 160 and 161, and a connection to supply line 237a through line 255. When the spool 160d of valve 160 is placed in the forward position, both pilot lines 176 and 176a blocked, and by appropriately positioning spool 161b, liquid from both circuits is applied to the ram in its forward or ejecting operation. In the return position, " B " Fig. 6, only the line 176a is blocked and so the ram 29 is only acted upon by fluid from the line 237a or half the pump's output. In a modification, Fig. 10, wherein all the wheel suspension units are of the rotary type, a levelling valve 265 is associated with wheel 6 on the left-hand side of the vehicle and is connected in series with the levelling valve 151 on the right-hand side by a line 266, and a line 267 controlled by a non-return valve 268 connecting with the connecting line 245 between the valve units 148. The connecting line 266 is on the right-hand side of piston 213 in valves 265 and 151. The centralizing accumulator pressure unseats the valve 268 when the pressure in line 245 is below that required to maintain the wheels 6 in a neutral position, e.g. when the vehicle tends to settle at its rear end. If only one cam is actuated, pressure from the central circuit cannot be admitted to the cross-over line 245. Limit stops 206, 207, 208 and 209 each comprising a piston and cylinder 210d, 210e connected to an abutment member pivoted to the vehicle side are provided for the wheels 3 and 4 and are moved by fluid pressure in the line 210 (corresponding to the " sprung " position), Fig. 5, into obstructing relationship with a stop element 210b on the wheel suspension member.