Husqvarna PT26D Workshop Manual page 55

DESIGN AND FUNCTION
Hydraulic pump for drive system
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Circuit diagram hydraulic pump
The hydraulic pump for the drive system alternates input and output depending on how the pump is set. The oil for
the pump's feed pressure is supplied by the gear pump (8), which sits on the engine. The pressure is regulated by
the pressure limiting valve, which is located in the hydraulic pump for the drive system, to 1.8 MPa (18 bar) and the
oil is piped as feed pressure to the pump's suction side via one (of two) check valves. The pump must also be
cooled and lubricated. This is done by part of the oil leaking past the pistons in the pump's cylinder drum and filling
the pump housing. This oil is then piped to the tank via the cooler (12). The pump supplies oil to the valve block for
transmission (6) and the flow is distributed to both wheel shafts' wheel motors via the flow distributor In certain situ-
ations, the flow distributor is disengaged by the parallel solenoid valve (3). The block's other solenoid valve controls
the function between front- and four-wheel drive. From the control unit's excess flow valve, in case of low pressure
in the valve block for transmission, comes auxiliary pressure/filling pressure (= feed pressure).
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