Komatsu 75001, Shop Manual

Page: 427 / 1293

SEN03837-01
30-120
6
WA250, 250PZ-6
120 Testing and adjusting, Part 2
Testing and adjusting HST oil pressure
Testing low-pressure relief pressure (basic
pressure of work equipment PPC circuit)
[Testing with monitoring function]
See “Testing high-pressure cut-off oil pressure”.
[Testing with tools]
1.
Remove low-pressure relief pressure mea-
surement plug (4) (10 mm, P = 1.25 mm) from
under the machine.
a The oil pressure pickup plug is installed to
the accumulator bottom near the lower
right of the transfer on the right side of the
rear frame.
2. Install a nipple, then connect oil pressure
gauge L (6 MPa {60 kg/cm
2
}).
3. Place the directional lever at N, run the engine
at high idle, and measure the low-pressure
relief pressure.
4. After finishing the work, remove the measuring
instruments and return the removed parts.
Testing servo piston control pressure (DA pres-
sure)
1. Remove floor frame cover (5) (bottom left of
operator's cab).
2. Remove servo piston control pressure mea-
surement plug (6) (DA pressure) (10 mm, P =
1.25 mm).
3. Install nipple L [3], then connect oil pressure
gauge L [1], L [2] (6 MPa {60 kg/cm
2 }).
4. Place the directional lever at N, run the engine
at high idle, and measure the control pressure
when the brake pedal is depressed and when it
is released.
a The brake pedal is connected to the inch-
ing valve and controls the control pres-
sure.
5. After finishing the work, remove the measuring
instruments and return the removed parts.