Bad Boy 1022H - Page 86

B22W-202010
4
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CHAPTER 4 HST SYSTEM 1022H TRACTOR
• MOTOR
<Figure-c> shows a rotation parts in Axial Piston
Pump, and 9 pistons are inserted to Cylinder Block. At
the end of Cylinder Block, there is Valve Plate with two
crescent passages (Ps and Pd), and the two crescent
passages are connected to inlet pipe and discharge
pipe respectively.
In this condition, if having high pressure oil delivered
from Ps Port, piston will be pressed and Swash Plate
will be affected by Force (F). The force component
(Ft) of this Force’s rotation direction rotates Cylinder
Block, which makes its Spline get in and generated
torque in the Shaft towards ω and nally works Motor.
Output torque of Motor is calculated as follows:
T = ( P · Dm · ηm ) / 2π ( N.m )
Dm : Motor Capacity (cm
3
/rev)
P : Working Pressure (MPa)
ηm : Torque Efciency (%)
The number of rotation is changed by ow pressure,
and it is calculated as follows:
N = ( Q.η vm ) / Dm
Q : Inow Quantity (cm
3
/min)
η vm : Motor Volume Efciency
At this time, hydraulic oil (operating oil) is discharged
from Pd Port. Reversely, if drawing pressure oil from
Pd Port, it rotates contrary to the above expression.
HST Circuit has an internal gap, so it is equipped with
CHARGE CIRCUIT to compensate the weak point. Oil
discharged from CHARGE PUMP is to be supplied to
Pump and Motor through
CHECK VALVE, discharged from CHARGE PUMP,
ows into the case through low
- Pressure Relief Valve and comes back to tank.
1. NEUTRAL (LEVER : Neutral Position)-------------
-----------------------------------------------Figure-d
A variable pump does not work even if rotating the
input shaft of HST. Oil it not supplied from pump to
motor and output shaft does not rotate. Two high-
pressure passages linking pump and motor are
connected to charge circuit.
The remaining oil that is supplied to main circuit
via Check Valve, discharged from GEAR PUMP
(CHARGE PUMP), ows into the case through low-
pressure Relief Valve and comes back to tank.
K19W087A
Figure-c
K19W088A
Figure-d
6.2 CHARGE CIRCUIT
6.3 HST OPERATION