TM-9-2320-273-10
TRUCK, TRACTOR, LINE HAUL; LIGHT EQUIPMENT TRANSPORTER; TRUCK CHASSIS; MEDIUM EQUIPMENT TRANSPORTER
TECHNICAL MANUAL; OPERATOR’S MANUAL
DECEMBER 2012
TM-9-2320-273-10 - Page 190 of 452
EFFICIENT AND ECONOMICAL DRIVING TECHNIQUES (M915A1) - CONTINUED
Using Engine for Braking
WARNING
The engine brake loses its effectiveness to control speed of
tractor when tractor is pushed by additional weight of trailer
on downhill grades. Failure to downshift transmission to
lower gear range and use service brakes to keep tractor and
engine speeds under control may result in damage to
equipment and possible injury or death to personnel. Seek
medical attention in the event of an injury.
Do not use engine retarder on slippery road surfaces. Using
engine retarder on wet, icy, or snow covered roads may
result in loss of vehicle control. Failure to comply may result
in damage to equipment and injury or death to personnel.
Seek medical attention in the event of an injury.
1. To operate the engine retarder, switch ENGINE RETARDER switch
(Figure 15, Item 4) to the number of cylinders desired for braking action
(WP 0005). To slow tractor, move foot completely off accelerator pedal
(Figure 16, Item 1) and depress engine retarder control pedal (Figure 16, Item 2).
2. To maximize the braking effect of the engine retarder, keep transmission in a gear
range that matches road speed and rated engine rpm. Engine braking is increased
by either downshifting to the next lower gear range and/or placing the ENGINE
RETARDER switch (Figure 15, Item 4) to MED position (Figure 15, Item 2) or
HIGH position (Figure 15, Item 1).
3. When using the engine retarder on a downhill grade, select the same gear range
necessary for climbing the same grade. To increase braking effect of engine
retarder, either downshift transmission to the next lower gear range and/or switch
the ENGINE RETARDER switch (Figure 15, Item 4) to MED position
(Figure 15, Item 2) or HIGH position (Figure 15, Item 1). To decrease braking
effect of engine retarder, either upshift transmission to higher gear range and/or
switch ENGINE RETARDER switch (Figure 15, Item 4) to MED position
(Figure 15, Item 2) or LOW position (Figure 15, Item 3).
Figure 15. Engine Retarder Switch.
1
2
3
4
RETARDER
ENGINE
TM 9-2320-273-10
0010
0010-24
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