Maintenance
Operation Manual - All
S
P Rock Valve Model
s
104
revD
a
te
General Maintenance Tip
s
Torque
S
pecification
s
When performing maintenance that requires removal
and replacement of bolts, it is very important to adhere
to the torque specifications that apply to that bolt
(Figure 44).
The graphs in Figure 44 demonstrate what happens to a
bolt if it is not properly torqued. The dashed line
represents the prestress on the bolt. As the device that
uses the bolt goes through its normal functions, the bolt
in example “A” gets stretched and relaxed with every
duty cycle, because the bolt is prestressed under the
maximum force of the cycle. In example “B”, the
prestress of the bolt has been raised to more than the
maximum force of the duty cycle, so the bolt doesn’t
ever feel the cycle. In this example, bolt “B” would last
MUCH longer than bolt “A”. The torque specifications
for bolts used on Schwing equipment are found in the
Appendix section of this manual.
Adju
s
ting relief valve
s
.
While adjusting a relief valve is not normally a
dangerous procedure, you should remember that it has
the potential to cause trouble. The main thing to watch
out for is this: Sometimes people that don’t know better
will have a problem with a machine and begin trouble
shooting by raising the relief valve setting. When that
doesn’t help, they forget to lower it back down. Now
when you check the pressure by creating a hydraulic
dead block, the pressure is set too high. In extreme
cases, this can cause hoses or fittings to burst, or other
component failure. To be safe, you should begin the
adjustment procedure by turning the adjustment device
to the lowest possible setting, then bring the device
back up to the proper setting.
Removal of
s
afety device
s
.
Sometimes you will have to remove a safety guard or
other safety device in order to perform maintenance.
For these situations, you must take extra care to be sure
of your own safety, and that of your co-workers. If you
have to put your hands, feet or any other body part into
a part of the machine that would normally be guarded,
be sure that the machine is turned off and that the key is
in your pocket. If there is more than one key in
existence, you should also put a “DO NOT OPERATE”
sign on the controls or over the start switch. Lock out
tags were provided with you pump when it was
delivered (Figure 45).
Before restarting the machine after performing
maintenance, be sure to put away all tools, parts and
supplies, and clear the area of personnel. If your
company has a “lock out - tag out” policy in place,
abide by it.
Concrete pumps are big enough to hide a man. Be sure
to yell “clear” before starting the unit at any time, and
allow time for response before proceeding.
SWG98n175.eps
Figure 44
S
howing the effect
s
of proper pre
s
tre
ss
ing of a bolt.
Front
Back
DANGER
LOCKED
OUT
DO NOT OPERATE
This lock/tag may
only
b
e removed
b
y:
Name ________________
Dept. _________________
Expected Completion_____
XYZ Company No. 12
3
45
DANGER
This unit has
b
een
LOCK OUT
Only the individual who
signed the reverse side
may remove this lock/tag.
Remarks: ________________
________________________
________________________
________________________
________________________
________________________
lockout.eps
Figure 45
Lockout/Tagout provided with unit
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