Control Levers - Gradall G660 Combined Service Manual

GRADALL G-660 (Starting Lot 57)
TESTING HYDRAULIC SYSTEM
Before testing Hydraulic System, make these checks:
Engine R.P.M. Check Power Unit with Tachometer
with the clutch engaged. The engine should turn at proper
R.P.M. See specification page at rear of this section.
Clutch. Engage and disengage the clutch to make sure
that no slippage is occurring. You should feel a definite
resistance as the clutch linkage slips over center and
engages.
Reservoir. Remove reservoir covers and inspect filters.
Feel bottom of the reservoir for dirt. Also drain some oil
into glass bottle, and allow to settle. If dirt, or water is pre-
sent, drain reservoir, clean it, and refill with new hydraulic
oil to the proper level. Start engine and bring oil to operat-
ing temperature. NEVER TEST PRESSURES WITH
COLD OIL.
PUMPS
Speed is determined by the volume of oil being used.
Power is determined by the pressures built up to perform
work. Slow action in a circuit indicates that either the
pump itself is not putting out the required volume or that
leakage is taking place internally.
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.
TOOLS NEEDED TO TEST SYSTEM
Hydraulic Pressure Gauge. This gage is a standard
item in your tool kit. It reads from 0 to 3000 psi. Many cus-
tomers prefer to use it with a 10 foot hose extension. The
hose buffers any indicator vibrations.
Hydraulic Flow Meter. This meter measures pump
efficiency in both pressure and volume. You can measure
actual pump output, both with no resistance and with a
pressure loading subjected against it. See your W & S dis-
tributor for a flow meter test.
HOW TO TEST PUMPS
Insert a flow meter intothe output (pressure port) of the
pump, and observe actual pump production. Tests should
be made for volume with no resistance; then retested when
resistance is placed in the meter to equal the pump relief
valve setting; An inefficient or worn pump may pump full
volume of oil under no load, but almost nothing under full
resistance.
The service test R.P.M. rating of the pumps output is
listed on the specification page (back of this section). Flow
meter readings will show less than the theoretical rating
because of back pressures, the thinning out of oil because
of temperature, and the resistance caused by relief valves.
At 180° flow meter reading will show less gallonage than
at 120°. As a pump works, the pump output will also be
reduced depending upon the degree of internal wear.
Testing pumps with Flow Meter.

CONTROL LEVERS

The Gradall is operated and tested by the movement of
hand control levers and foot pedals to actuate the respec-
tive valve plunger.
Movement of Control Levers for testing.
1
PUMPS