Gradall 534B (9103-1390) Service Manual - Manual (Page 79)

INTRODUCTION
Before testing the hydraulic system it is important
that you read and understand System Operations of
534B, and the Safety Manual. Then make the
following checks:
Engine RPM: Using tachometer, check engine rpm
at both idle speed and high speed (with the
accelerator fully depressed). The tachometer
reading should be:*
Idle ........................900 rpm approx.
High ......................2800 rpm approx.
Next, check with the boom retracted fully while
holding back on the control lever. It should read
about 2600 rpm.
*If unahle to ger proper rpm call in a qualified
engine mechanic and follow manufacrurer ’s
recommendarions.
Reservoir: Drain some oil from the plug at the
bottom of the reservoir into a glass bottle and allow
it to settle. If dirt or water is present, drain and clean
reservoir, replace filter and fill with new hydraulic
fluid to proper level. Start engine and bring oil to
operating temperature.
Never test pressures with
cold oil.
WA R N I N G : D O N O T O P E R AT E
G R A D A L L M AT E R I A L H A N D L E R
U N L E S S F L U I D I S AT P R O P E R
LEVEL:
Form No. 48731
PUMPS
Speed of hydraulic functions is determined by the
volume of oil provided for the functions. Power
(force) is determined by the pressure built up to
perform work. Slow action in a circuit indicates that
either the pump is not putting out the required
volume or that leakage is taking place.
The ability of a pump to build up pressures strong
enough to open the pump relief valve is one
indication of pump efficiency. However, it is
possible for the pump to build up this pressure, and
still not be putting out the required volume of oil.
BLEEDING OFF CIRCUIT PRESSURE
To remove high residual pressure in the hydraulic
system, do the following:
1. Place forks on ground and idle the engine. Set
parking brake.
2. Move all control levers back and forth several
times. Shut off engine.
3. Move all control levers back and forth again.
4. If cylinder work is going to be done, loosen
mounting bolts on holding valve on cylinder to
allow any trapped pressure to escape. Tighten
bolts.
BE EXTREMELY CAREFUL WHEN DISCON-
NECTING OR LOOSENING ANY HYDRAULIC
FITTINGS.
Gradall is a registered trademark for hydraulic excavators.
hydraulic material handlers, and attachments built by The
Gradall Company
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