Blastrac BMS-270LPII, Руководство по эксплуатации

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Revision B
Revised 5/20/2003 12:33 PM
47
Operating Instructions BMS-270LPII
Hydraulic System
10.2 Hydrostatic Pump
Item 1 (P002336) on Service Drawing 700-SD0010 is a tandem in-line hydrostatic pump.
This variable displacement pump has a mechanical control arm connected to the swashplates.
When the operator moves the motion control joystick, the swashplate tilts. This titling results
in fluid flow to the pump, which is directly proportional to the operator’s control movements.
As the operator makes an opposite control movement the swashplate reverses its tilt angle
and reverses the fluid flow. This is a tandem pump, therefore there are two pumps available
for the wheel drive motors. The right drive wheel uses the rear pump of the tandem and the
left drive wheel used the front pump of the tandem. The motions control joystick is
mechanically connected to the pumps by a trunion shaft at all times. As viewed from the rear
of the multiscraper, a left control movement will cause the right drive wheel to rotate forward
and the left drive wheel to rotate in reverse turning the multiscraper to the left with a virtually
zero turning radius.
Since there is natural leakage in any piston pump and the piston pumps are part of the
closed loop circuit, the fluid must be replenished or the closed loop circuit would quickly
run out of fluid. The hydrostatic pump is equipped with two charge pumps, one for each
piston pump in the tandem set-up. As fluid is lost in the piston pumps, it is returned to
the hydraulic tank via the case drains (the “D” ports of item 1). The charge pumps draw
fluid from the hydraulic tank and supply the piston pumps with a constant pressure,
variable flow of fluid. The charge pumps will supply the piston pumps with the required
fluid flow at all times. The excess fluid not used by the piston pumps returns to the
hydraulic tank by way of the case drains.
WARNING: Always have the control handle in the center position when starting
the BMS-270LPII. If the handle is not in the center position, the piston pump
will start “on-stroke” sending a rush of fluid into the pump and causing damage
to the pump. Moreover, the machine could move rapidly possibly causing
serious injury or death.