Periodic Inspection; Maintenance; Wear Limits; Wear Adjustment - Danfoss Airflex DBBS Installation, Operation And Maintenance Manual

DBBS Brakes
3.3

Periodic Inspection

3.3.1 As the friction material wears, the brake torque
will be reduced somewhat and adjustment of the
stopping position controls (flow control or limit
switch) will be necessary. See the Maintenance
section for the friction material wear limit and
replacement procedure.
3.3.2 Periodically inspect the brake for proper operation
particularly if excessive heating of the disc (58) has
been experienced or is suspected of having occurred.
See 'WARNING' below. Excessive heating of
brake components can be caused by disc dragging,
excessive E-Stops, low air pressure, warping of the
discs, or operating the brake beyond its designed
capability.
Warning
If the brake is subjected to heat, the discs (58) may
shrink causing a condition whereby the discs will get
stuck to the gear, limiting the axial movement. This
condition will cause failure of the brake to develop
full torque.
Warning
Failure to develop full torque can cause drastic
equipment failure, personal injury and/or death.
3.3.3 Periodically check for air leakage in the area of the
piston seals (21, 23). For replacement, refer to the
Maintenance section.
3.3.4 Periodically observe the discs with the brake
Figure 3
released. Causes of dragging discs may include wear
or contamination of the gear or disc splines, disc
imbalance, warped discs, or excessive shaft float.
3.3.5 Pneumatic and electrical control interlocks should
be periodically checked for correct settings and
operation.
3.3.6 Periodically remove the brass drain plug (105) and
purge condensation from the cylinder. Replace the
brass drain plug with sealant and check for air leaks.
4.0

Maintenance

Warning
Prior to performing any maintenance on the DBBS
brake, make sure the equipment is in, and will remain
in, a safe condition. Never service a brake supporting
a load.
4.1

Wear Limits

4.1.1 Wear limits for the DBBS components are shown
on Table 7. If any wear limit has been reached or
exceeded, that component must be repaired or
replaced.
4.2

Wear Adjustment

Note
Refer to Figure 4 for illustration of the friction
material wear groove for the size 20DDBBS, 25DBBS
and 38DBBS brakes and friction material wear step
in the size 50DBBS brakes. Refer to Figure 6, Figure
7, Figure 8 & Figure 9 for an illustration of the wear
gaps on all DBBS sizes. On single and multiple disc
units, the friction material must be replaced when
worn to the bottom of the groove on the friction
material or to the bottom of the step on the friction
lining on the size 50 brakes. Multiple disc brakes,
however, are manufactured with wear spacers that
allow for wear adjustment when the 'Gap Required
for Adjustment' has been reached per the values
in Table 8. Typically, multiple disc brakes have a
quantity of wear spacers equal to the number of
discs minus 1. For example: a 450DBBS brake has 4
discs and 3 wear spacers. The exception to this rule
is the 420DBBS that has additional 'thinner' spacers
that will require four (4) adjustments. The number of
wear spacers will dictate the number of adjustments
before the brake requires complete disassembly for
friction disc replacement. Spacers are removed to
correct for wear. One set of spacers is removed for
each wear adjustment.
Airflex DBB 8110 Brake Assembly E-CLCL-TT001-E
®
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