SUBSECTION 1OC
PROPEL ANTI-STALL CONTROL SYSTEM
GENERAL
the operator. The pump controller positions the swash-
plate proportional to input current. Therefore, the input volt-
This subsection provides the information necessary for
age to the control station and lever position determine the
troubleshooting the propel anti-stall control system used on
displacement of the pump.
this machine. Troubleshooting instructions are outlined to
permit isolation of the specific component(s) which may
have failed. Individual components of this system are not
field serviceable: if a component is faulty it must be re-
placed.
An engine speed potentiometer is used to sense the throt-
tle setting. The potentiometer is connected to the throttle
linkage located below the circuit breaker panel at the rear of
The information in this subsection pertains only to the elec-
the operator's module. A magnetic pulse pickup is used to
trical components in the propel anti-stall system. Refer to
sense engine speed. The pulse pickup is fastened to the
Subsection 9A for propel hydraulic system troubleshooting
lower left hand side of the engine flywheel housing. When-
information.
ever engine speed falls below the rpm expected at a given
throttle setting, the anti-stall module electronics will auto-
matically reduce the input voltage to the control station. The
reduced input voltage proportionally destrokes the pumps,
thereby preventing the engine from stalling. A switch on the
DESCRIPTION
anti-stall module can be used to bypass the anti-stall elec-
tronics. Switching into the manual mode supplies the con-
The anti-stall control system automatically destrokes the
trol station with constant battery voltage.
propel pumps to prevent engine stalling when the machine
is propelled. In addition to the pump/motor hydrostatic
transmissions, the propel system includes an electronic
anti-stall module, an engine speed potentiometer, two
pump controllers, a magnetic engine speed pickup and a
propel control station (see Figure 10C-1).
TROUBLESHOOTING
GENERAL. Before any service is performed on this system,
This machine is equipped with two propel motors and two
this subsection and Subsection 9A should be thoroughly re-
propel pumps. One pump/motor transmission drives the
viewed. Adequate servicing depends upon a good under-
right side of the machine while the other pump/motor
standing of the control system. To perform the tests and
transmission drives the left side of the machine. One propel
minor repairs described in this subsection, the following
pump controller is located on the side of each pump. The
tools are required: a 25-50 watt soldering iron, a volt-ohm-
pump controllers provide flow to the pump swashplate con-
ammeter, a blade screwdriver and a 1/8 inch Allen wrench
trol pistons and respond to displacement of the swashplate
(2-1/2 inches long).
through a feedback linkage and spring followup.
Table 10C-1 is provided to assist in isolating and correcting
Electrical current input into the pump controllers is pro-
problems that may occur in the propel anti-stall control sys-
vided by a dual axis propel control station located in the op-
tem. The tests listed in the troubleshooting chart are de-
erator's module. The control station outputs current pro-
scribed in detail in the paragraphs following the chart.
portional to input voltage and the lever position selected by
