Abstract: A drive apparatus for a vehicle, the apparatus comprising a hydraulic pump, two control valve assemblies, and two pairs of hydraulic drive assemblies. The control valve assemblies are hydraulically connected in parallel, and in an operational condition hydraulic fluid is pumped through the control valve assemblies by the pump to drive the hydraulic drive assemblies, and wherein each control valve assembly proportionately distributes hydraulic fluid to a respective pair of the hydraulic drive assemblies in response to the hydraulic loads of the respective hydraulic drive assemblies of the respective pairs of hydraulic drive assemblies.

Abstract: A hydraulic drive apparatus comprises a main pump for pumping hydraulic fluid through a hydraulic load, a charge pump for continuously pumping pressurized hydraulic fluid to the main pump, and a hydraulic fluid cooler. At least a portion to the hydraulic fluid pumped through the hydraulic load is returned under pressure to the charge pump and the charge pump pumps the pressurized hydraulic fluid through the hydraulic fluid cooler to the main pump.

Abstract: An engine after-cooling system (10) comprises an after-cooler (11) for cooling compressed air which is output from a compressor for combustion by an internal-combustion engine, a heat exchanger (19) for cooling a coolant which is output from the after-cooler (11), a pump (21) for continuously pumping the coolant through the system (10), an outlet air temperature sensor (27) for sensing the temperature of the compressed air after being cooled by the after-cooler (11), a coolant temperature sensor (17) for sensing the temperature of the coolant output from the after-cooler (11), and a controller (26) for controlling the flow-rate of coolant through the system (10) in response to the sensed air and coolant temperatures.