Pedals; Service Brake Pedal; Dynamic Retarder Pedal; Throttle Pedal - Komatsu 730E Operation & Maintenance Manual

OM3214
Operator Cab and Controls

PEDALS

SERVICE BRAKE PEDAL

Service brake pedal (2, Figure 32-4) is a foot-operated
pedal which applies the service brakes.
NOTE: In some optional installations, the service
brake pedal may not be present, because it is
incorporated into a single pedal function with retarder
pedal (3).

DYNAMIC RETARDER PEDAL

Dynamic retarder pedal (3, Figure 32-4) is a foot-
operated pedal which allows the operator to slow the
truck and maintain a safe productive speed without
the use of the service brakes. For normal truck opera-
tion, only dynamic retarding is used to slow and con-
trol the speed of the truck. Refer to Grade/Speed
Warning chart (8, Figure 32-1) to determine the maxi-
mum safe truck speeds for descending various
grades with a loaded truck. Apply the service brakes
only when dynamic retarding requires additional brak-
ing force to slow the truck speed quickly and to com-
pletely stop the truck.
When dynamic retarding is activated, the engine rpm
will automatically go to an advance rpm retard speed
setting (usually 1250 rpm, see note below.) Dynamic
retarding will be applied automatically if the speed of
the truck reaches the predetermined overspeed
retard setting. Dynamic retarding is available in FOR-
WARD/REVERSE at all truck speeds above 0 kph
(mph) but is available in NEUTRAL only when the
truck speed is above 5 kph (3 mph).
NOTE: The exact engine speed in retarding may vary
(1250 - 1650 rpm) due to the temperature of certain
components, This is controlled by the Statex III
control system.
Optional - Dual Function/Single Pedal
The dynamic retarding/brake pedal is a single foot-
operated pedal which controls both retarding and
service brake functions. Thus, the operator must first
apply, and maintain, full dynamic retarding in order to
apply the service brakes.
When pedal (3) is partially depressed, dynamic
retarding is activated (actuation is modulated).
Pressing the pedal further applies full retarding. Dur-
ing full retarding the service brakes also begin to
apply. Completely depressing the pedal causes full
application of both the dynamic retarding and the ser-
vice brakes.

THROTTLE PEDAL

Throttle pedal (4, Figure 32-4) is a foot-operated
pedal which allows the operator to control the engine
rpm, depending on the pedal depression.
FIGURE 32-4. PEDALS
1. Cab Floor
2. Service Brake Pedal
Operation - Section 32
Page 32-3
3. Dynamic Retarder
Pedal
4. Throttle Pedal