TM 5-3805-248-23-1
GENERAL MAINTENANCE INSTRUCTIONS
NOTE
Refer to WP 0018 00 for Electrical General Maintenance Instructions.
SCOPE
These general maintenance instructions contain general shop practices and specific methods you must be familiar with
to properly maintain the 621B Scraper. You should read and understand these practices and methods before starting mainte-
nance tasks on the machine.
WORK SAFETY
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1.
Before starting a task, think about the risks and hazards to your safety as well as others. Wear protective gear such as
safety goggles or lenses, safety shoes, rubber apron or gloves. Protect yourself against injury.
2.
Observe all WARNINGs and CAUTIONs.
3.
When lifting heavy parts, have someone help you. Ensure that lifting equipment is working properly, that it is appropri-
ate for the task assigned, of sufficient load capacity and secured against slipping.
4.
Always use power tools carefully.
5.
Before beginning a procedure, ensure that the following conditions have been observed, unless otherwise specified:
a.
Machine must be parked on level ground with implements lowered to the ground.
b.
Transmission must be in N (Neutral) with transmission lock lever in locked position.
c.
Engine must be off.
d.
Components that are hot at operating temperatures (i.e., cooling, exhaust and hydraulic systems) must cool down
before they are removed.
e.
Components must, however, be at operating temperature to be tested.
f.
Battery disconnect switch must be in OFF position and batteries disconnected when performing electrical system
maintenance.
g.
Hydraulic system pressure must be relieved before disconnecting any hydraulic system line or fitting. Refer to
Relieving Hydraulic System Pressure, below.
RELIEVING HYDRAULIC SYSTEM PRESSURE
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WARNING
DO NOT remove hydraulic tank filler cap or disconnect or remove any hydraulic system line or fitting
unless hydraulic system pressure has been relieved. Hydraulic system pressure can be over 2,500 psi (17,238
kPa), even with engine and pump OFF. To relieve pressure, lower all hydraulic attachments to the ground
and shut down engine. Move control levers through all operating positions, then SLOWLY loosen hydraulic
tank filler cap. After maintenance, tighten all connections before applying pressure. Escaping hydraulic fluid
under pressure can penetrate the skin, causing serious injury or death.
1.
Lower all machine implements to the ground.
2.
Shut down engine.
3.
Move all control levers through all operating positions. Return levers to HOLD position.
4.
Slowly loosen filler cap and allow any pressure to escape.
