Page 591 - Mechatronics with Experiments

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JWST499-Cetinkunt
JWST499-c07
ELECTROHYDRAULIC MOTION CONTROL SYSTEMS 577

Dozer (Track type tractor)

Skid steer loader (Track type)
Excavator
FIGURE 7.110: Hydrostatic transmission (drive) application in tracked vehicles.

requires a transmission system with adjustable gear ratio. The gear ratio of the hydrostatic
transmission is determined by the ratio of the pump and motor displacement. In older
hydrostatic transmission designs, the pump is variable displacement and the motor is fixed
displacement. However, the current trend is towards designing hydrostatic transmissions
with both pump and motor being of the variable displacement type.

Hydrostatic drive 1
Motor 1
p_p1 Track 1
Pump 1
Gear
D_p1 D_m1 reducer
R_s
w_m1
p_r1 Ng
w_eng T_m1 w_track V_load
T_eng T_track F_load
Engine
p_p2 Motor 2
Pump 2
D_p2 D_m2
Gear
reducer
R_s
p_r2 w_m2 Ng Track 2
T_m2
Hydrostatic drive 2
(Charge and flushing circuits, relief valves are not shown)
FIGURE 7.111: Hydrostatic transmission circuit and its components.