SRT45 Off-Highway Truck
3-14
Safety, Operation and Maintenance Manual
The retarder is off when the lever is fully
forward and is applied as the lever is pulled
back. Rear disc brake retarder can obtain
different retardation by shifting handle from
front to rear. Maximum retardation is obtained
when the lever is in the fully back position.
(1) Retarder operation
Before the machine crests the top of a grade
and starts down, the operator should slow the
machine with the service brakes and downshift
to the gear range which would be used to
ascend the grade. The retarder should be
applied before starting the descent. Machine
downgrade speed (with the retarder applied
as required) in the gear range selected should
be high enough to keep the engine operating
at governed speed with the throttle closed
(operator's foot off the accelerator pedal).
This will ensure maximum oil circulation and
cooling. If the rate of descent is too slow, the
transmission should be upshifted to the next
highest gear range. If the rate of descent is too
fast, the gear range selected is too high and
the operator must slow the machine by using
the service brakes, then downshift into a lower
gear range which will allow a safe descent and
efficient retarder operation.
The two retarders can be used at the same
time, it is strongly recommended that just one
of them is used and the transmission retarder
is prior. Only when maximum transmission
r e t a r d a t i o n i s o b t a i n e d a n d a d d i t i o n a l
retardation is required, the rear disk brake
retarder be used.
N o t e :
I n o r d e r t o o b t a i n t h e m a x i m u m
r e t a r d a t i o n a n d c o o l i n g e f f e c t d u r i n g
retardation, the engine speed should be
maintained as high as possible without
exceeding the maximum recommendation.
(2) Oil temperature - rear disc brake
The disc brake hydraulic temperature warning
indicator on the instrument panel will illuminate
and an electric horn will sound if the oil flowing
through the disc brake assemblies overheats.
Controls and Operating