SYSTEM / Hydraulic System HST CIRCUIT Outline: • The HST (Hydro-Static Transmission) circuit is a closed circuit, and consists of the HST pump and the HST motor. • The HST pump is directly driven by the engine power. The HST motor turned by pressure oil from the HST pump. • The output power of the HST motor is transmitted to the reduction gear / rear axle → the propeller shaft → the front axle → the tire in sequence. NOTE: The reduction gear is connected to the rear axle.
• The HST pump has a built-in HST charging pump. The HST charging pump is directly driven by the engine power and draws hydraulic oil from the hydraulic oil tank. The hydraulic oil is added to the low pressure side in the closed circuit in the HST pump and the HST motor through the HST filter. • Pressure oil from the HST charging pump also cools the HST pump and the HST motor. Pressure oil from the HST charging pump is the oil pressure source of the HST pump displacement angle control.
HST Pump Engine HST Charging Pump
HST Filter
Hydraulic Oil Tank HST Motor
Reduction Gear
Rear Axle
Front Axle
T4FG-02-02-007
Propeller Shaft
T2-2-13
