Wacker Neuson 28Z3, Service Manual

Page: 79 / 264

SHB 28Z3 EN – Edition 2.0 * 28z3s312.fm
3-33
Maintenance
Pressure check of variable displacement pump P1
Hydraulic supply for boom, bucket and right-hand side drive functions
Checking primary pressure limiting valve 1 (PPLV 1)
☞
Connect a pressure gauge to measuring port MP 1 40/1
☞
Retract the boom ram or the bucket ram as far as it will go at maximum
engine speed
☞
Check and make a note of the pressure value.
Checking pressure drop
☞
Retract the boom ram or the bucket ram as far as it will go at maximum engine speed
☞
Swiftly reduce engine speed from maximum to minimum -> pressure drop
☞
Check and make a note of the pressure value.
➥
Pressure drop should not be more than 10 % of the specified value
Setting primary pressure limiting valve 1 (PPLV 1)
☞
Adjust the pressure at the primary pressure limiting valve (PPLV 1) 41/A on the main
valve block
☞
Slacken the locknut of the pressure limiting valve
☞
Unscrew the pressure limiting valve until you can read off a pressure drop on the
pressure gauge
➥
The valve seat may be stuck and must be slackened first
☞
Adjust the pressure limiting valve and tighten the locknut
☞
Check the primary pressure limiting valve 1 and the pressure drop once adjustment is
over
Also check with the extend boom, the extend/retract bucket and with the right-hand
side forwards/reverse drive functions!
Fig. 40: Measuring port P1
1
Fig. 41: Primary pressure limiting valve 1
A