
31200243 93
Operation Section
Equipment Lowering with Loss of
Hydraulic Power
Lowering the boom with the engine stopped can cause
personal injury or death.
Keep all personnel away from the boom drop area when
lowering the boom with the engine stopped.
Personal injury can result from not following the
specified procedure.
To avoid personal injury, follow the procedure as
specified.
Lowering a raised boom increases the outreach of the
load. This can reduce the forward stability of the
machine resulting in machine tip over. This can cause
injury or death to the operator or other personnel in
the work area. Always retract the boom, if possible,
before lowering it.
The cylinder for retracting the boom, and the cylinder for
lowering the boom are equipped with load control
valves. The load control valves lock oil in the cylinders if
hydraulic power is lost. The locked oil in the cylinders
prevents the boom from moving.
In most situations, the boom can be retracted and the
boom can be lowered from ground level if hydraulic
power is lost.
If the angle of the boom is too low you may not be able
to retract the boom.
If the boom cannot be retracted, it might be possible to
lower the load to ground level without retracting the
boom first. Assess the weight of the load and consult
the appropriate load chart in order to determine that the
load can be lowered in this way without causing the
machine to tip forward. Do not attempt to lower the
boom unless you are satisfied with the stability of the
machine. You must be sure that the boom can be
lowered without hitting an obstacle.
Due to the size of the hydraulic tank, it is possible to
return 12 L (3.17 US gal) of oil to the tank more than
the tank capacity. This volume of oil must be removed
by the following procedure before lowering the boom or
retracting the boom from full stroke.
Procedure for Draining Hydraulic Tank
Hot oil and hot components can cause personal injury.
Do not allow hot oil or hot components to contact skin.
NOTICE
Care must be taken to ensure that fluids are contained
during performance of inspection, maintenance, testing,
adjusting and repair of the product. Be prepared to collect
the fluid with suitable containers before opening any
compartment or disassembling any component
containing fluids.
Refer to Special Publication, NENG2500, "Caterpillar
Dealer Service Tool Catalog" for tools and supplies
suitable to collect and contain fluids on Caterpillar
products.
Dispose of all fluids according to local regulations and
mandates.
Illustration 143 g01202853
Protection cover
1. In order to open protection cover (3), unlock lock (2)
and turn lock (4) counterclockwise. Then, pull latch
(1) outward.