TYM T233 HST, Руководство по обслуживанию

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SECTION 5. THEORY OF OPERATION
HYDROSTATIC SYSTEM
Function:
The hydrostatic system provides a means to transfer. Power from the engine to the final drive to the
wheels. It also provides infinitely variable speed control, forward or reverse, by foot pedal operation.
Principles of Operation:
The hydrostatic system is a closed loop fluid power system that consist of a charge pump on the left
front side of the engine.and an
THI piston pump/motor assembly, which is driven by a Flexible
coupler. Attached to the flywheel.
Fluid flow is controlled by changing the angle of the cam plate. This angle is controlled by the operator
through a mechanical linkage. Moving the respective directional pedal will move the position of the cam
plate.
Moving the cam plate off center changes the distance the pistons travel inside the piston bore of rotating
assembly. The direction that the cam plate is rotated from center determines the direction of fluid Flow
(forward or reverse). The number of degrees the cam plate is deflected.determines how much fluid will
be displaced(speed)
The hydrostatic pump provides hydraulic fluid to the hydrostatic motor through the back plate. Hydraulic The hydrostatic pump provides hydraulic fluid to the hydrostatic motor through the back plate. Hydraulic
fluid in the power train circulates in a closed loop. Fluid leaves the hydrostatic motor and is returned to
the hydrostatic pump,not the reservoir. Fluid that leaves this closed loop circuit,such as case drain, is
replenished by fluid from the charge pump.
Charge pump
The charge pump is a gear type positive displacement pump mounted to the right front side of the engine.
This pump provides pressurized fluid to the SCU (Steering Control Unit). Return oil from the SCU is
routed through the filter mounted to the front of the back plate,and then into the hydrostatic pump to
provide replacement fluid to the hydrostatic pump.
Hydrostatic Motor
The hydrostatic motor is an THI high torque axial piston motor. The motor is located on the rear of the
back plate. The hydrostatic motor drives the input shaft for a three speed range gear transmission which
transfers power to the wheels (See Final Drive Section)
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