Johnston VM502, Maintenance Manual

Page: 22 / 220

V Range 502
l
652
l
802 Maintenance Manual
MA2:2
Chapter - Hydraulic System
General Description
The hydraulic system may be divided into four hydraulic circuits fed from a common hydraulic reservoir.
1 Sweep system and load discharge. (VT and VS)
2 Options system for Supawash etc. (VT and VS)
3 Fan Drive (VS Only)
4 Transmission system. (VS Only)
Hydraulic filtration is provided by suction filters within the hydraulic tank, together with replaceable type
‘in line’ return filter mounted externally on the upper face of the hydraulic tank.
HYDRAULIC SYSTEM - INTRODUCTION
Test points
Test points are provided on the hydraulic system to carry out pressure checks.
Identification Function Machine Type
H -15Z6 Boost pressure, Reverse pressure and Antiskid VS
H -15Z7 Pump control pressure VS
H -15Z3 Boost pressure, Forward pressure VS
H -15Z2 Boost pressure VS
H -15Z5 Motor control pressure VS
H -15Z7 Coast pressure VS
H - 1Z2 Sweep system VT & VS
H -13Z5 Fan drive system VS
H -12Z2 Options system i.e. Supawash VT & VS
H - 8Z2 Discharge functions VT & VS
H -1472 Rear Wanderhose/Powaboom VT & VS
Body Discharge System
To set system pressures, select option 12 from the main menu.
System Pressure:
Select option 1 from menu 4.12 and follow the on screen prompts:
Connect a suitable 250 bar gauge to test point H-8Z2 on the discharge system block on the LH side of
the machine. Once connected, acknowledge this by pressing the rotary encoder on the display.
Start the engine and run at the appropriate speed and acknowledge by pressing the rotary encoder on
the display.
Check pressure and adjust if required relief valve H-8V3 on the discharge system block to 190 bar.
Acknowledge the pressure is set by pressing the rotary encoder on the display.
CIRCUIT PRESSURES
CAUTION:
Do not remove any hydraulic components without first ensuring that any
residual pressure has decayed. If in doubt ask.
NOTICE:
Only competent trained personnel should work on this equipment.
CAUTION:
Do not run the pressure test for more than 30 seconds.