TM 5-3805-290-23-1
THEORY OF OPERATION - CONTINUED
0003 00
BRAKE SYSTEM - CONTINUED
9.
Pressure Sensor.
a.
Service brakes can be actuated by left or right brake pedal. This is also true for transmission neutralizer. When
brakes are applied, pressure sensor located on brake control valve senses an increase in brake system pressure. A
signal is sent by sensor to machine ECM. Machine ECM will neutralize transmission. This allows full engine
power to be used in hydraulic system.
b.
When brake pedal is released, pressure in brake lines decreases. Pressure sensor sends a signal to machine ECM to
engage transmission.
c.
Transmission neutralizer override switch is a momentary switch. Transmission neutralizer is active when it is not
illuminated.
d.
When transmission neutralizer is deactivated, transmission will not shift to NEUTRAL when service brakes are
applied. Transmission neutralizer override switch will not be illuminated. This will result in increased wear on
brake discs.
e.
When transmission neutralizer is activated, transmission will shift to NEUTRAL when service brakes are applied.
Transmission neutralizer override switch will be illuminated. This will prevent transmission from driving through
brakes. This will lengthen brake life.
10.
Transmission Neutralization Point.
a.
Transmission neutralization point can be adjusted to operator preferences. Transmission neutralization point deter-
mines distance service brake pedal travels to neutralize transmission. Amount of pressure in service brake system
is determined by travel of service brake pedal. When service brake is applied, brake system pressure rises. When
pressure for brake system reaches transmission neutralization point, transmission disengages. This will reduce
pressure required to push pedal. When service brakes are disengaged, brake system pressure decreases. When
brake system pressure becomes less than 44 psi (303 kPa) from previous maximum pressure, transmission
engages.
b.
Service brake system pressure will rise higher when pedal is pushed quickly and vigorously. If service brake pres-
sure for is increased, pressure required to engage transmission is also increased.
c.
For example: Pressure on a service brake pedal rises to 220 psi (1,517 kPa). Transmission neutralization point is
set at 130 psi (896 kPa). When service brake pressure reaches 130 psi (896 kPa), transmission will neutralize. Ser-
vice brake pressure is held at 220 psi (1,500 kPa). When service brakes are released and service brake pressure
decreases to 175 psi (1,207 kPa), transmission will re-engage. If transmission neutralization point is set at 87 psi
(600 kPa) and service brake pressure reaches 220 psi (1,517 kPa), transmission will neutralize at 87 psi (600 kPa)
and transmission will still engage at 175 psi (1,207 kPa).
d.
A higher transmission neutralization point could be used when machine is on a slope. This will allow position of
machine to be held in place. A lower transmission neutralization point could be used to disengage transmission
during brake application to lengthen brake life.
e.
Transmission neutralization point is a programmable parameter in ET. Minimum setting for "Minimum Neutraliza-
tion Brake Pressure Setting" is 58 psi (400 kPa). Nominal setting for "Maximum Neutralization Brake Pressure
Setting" is 130 psi (896 kPa). Adjustable range for setting "Maximum Neutralization Brake Pressure Setting" is 87
to 160 psi (600 to 1,108 kPa).
f.
Display screen shows setting for "Minimum Neutralization Brake Pressure Setting" and "Maximum Neutralization
Brake Pressure Setting".
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