Pedal Controls - Komatsu 830E Shop Manual

PEDAL CONTROLS

THROTTLE PEDAL
The Throttle Pedal (4, Figure 5-4) is a foot operated
pedal which allows the operator to control engine
RPM depending on the amount of pedal depression.
SERVICE BRAKE PEDAL
The Service Brake Pedal (2, Figure 5-4) is a foot
operated pedal controlling a hydraulic valve, which
modulates pressure to the service brakes.
NOTE: Some trucks may be equipped with an
optional, single brake pedal. This pedal combines
the dynamic retarder and service brake functions on
the same pedal. Trucks with this option will not have
a pedal on the left side (2, Figure 5-4). Refer to
description below.
OPTIONAL DUAL FUNCTION/ SINGLE PEDAL
The optional Dynamic Retarding/Brake pedal is a
single pedal controlling both the retarding and ser-
vice brake functions. With this system, the operator
must first apply maximum dynamic retarding before
the service brakes may be applied.
When the pedal is depressed, the first portion of the
pedal stroke actuates an electronic pedal potentiom-
eter, sending an electrical signal to the Statex III
electrical system, initiating the dynamic retarding
function. The amount of retarding effort applied
depends on the amount of pedal depression, varying
from minimal when lightly depressed to maximum
when the pedal potentiometer signal reaches maxi-
mum voltage as more pressure is applied.
Further pedal depression starts application of the
service brakes as the hydraulic brake valve is actu-
ated. (A slight increase in pedal effort will be felt.)
Note that use of the service brakes also ensures
maximum dynamic retarding has been applied.
Completely depressing the pedal causes full applica-
tion of both dynamic retarding and the service
brakes.
N5-4
FIGURE 5-4. OPERATOR PEDALS
2. Service Brake Pedal
3. Dynamic Retarder
Pedal
DYNAMIC RETARDING PEDAL
The Dynamic Retarder Pedal (3, Figure 5-4) 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 operation, only dynamic retarding should be
used to slow and control the speed of the truck. The
Grade/Speed Chart (8, Figure 5-1) should always be
followed to determine MAXIMUM safe truck speeds
for descending various grades with a loaded truck.
Service brakes should be applied only when dynamic
retarding requires additional braking force to slow the
truck speed quickly and to bring the truck to a com-
plete stop.
When dynamic retarding is in operation, the engine
RPM will automatically go to an advance RPM retard
speed setting (usually 1250 RPM)*. Dynamic retard-
ing will be applied automatically, if the speed of the
truck reaches the predetermined overspeed retard
setting. Dynamic Retarding is available in "Forward/
Reverse" at all truck speeds above 0 mph/kph, but is
available in "Neutral" only when truck speed is above
3 mph (4.8 kph).
* 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.
Operator Controls
4. Throttle Pedal
N05056