GF42.35-P-3500A | ETS control mode, function | 4.7.96 |
MODEL 210.08 /28 with CODE (212a) Electronic Traction System (ETS)
P42.35-0209-76
ETS control mode pressure increase
The control process or valve positions shown in the example relate to the VR brake.
a Suction line
f High pressure
If one of the drive wheels tends towards spinning when starting off or accelerating, the control module introduces the ETS pressure increase control mode.
At the start of the ETS control the switchover solenoid valves (y18,y19) are switched (closed) into the "shut-off" position and the self-priming high pressure/return pumps (p1, p2) are actuated.
The inlet solenoid valve (y22) is actuated differently depending on the pressure in the brake calipers:
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A When a calculated pressure of 60 bar is reached in the brake calipers, the inlet solenoid valve (y22) is only opened during the pressure increase phases. The self-priming high pressure/return pump (p1) draws in brake fluid from the reservoir via the inlet solenoid valve (y22) and via the brake master cylinder.
B When a calculated pressure of > 60 bar is reached in one of the brake calipers, the inlet solenoid valve (y22) remains open continuously during the entire control process. The pressure to the brake caliper VR (5a) is built up by the self-priming high pressure/return pump (p1) via the solenoid valve (y8; not actuated - open).
The pressure limiting valve integrated in the switchover solenoid valve (y18) is used for high-pressure limiting (approx. 170 bar).
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P42.35-0210-76
ETS control mode pressure holding
The control process or valve positions shown in the example relate to theVR brake when a calculated brake pressure of
> 60 bar is reached in the brake caliper.
a Suction line
b Brake pressure
f High pressure
If a major brake intervention is no longer required to prevent drive slip, the ETS control mode pressure holding starts.
When a calculated pressure of 60 bar is reached in the brake caliper, the inlet solenoid valve (y22) is closed. As a result the brake pressure in the caliper cannot be increased by the high pressure/return pump (p1).
When a calculated pressure of > 60 bar is reached in the brake caliper, the pressure holding phase is introduced by actuation (closure) of the solenoid valve (y8).
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The solenoid valves (y8 and y9) are closed in this control phase, and as a result the pressure in the brake caliper remains constant. The self-priming high pressure/return pump (p1)is also actuated in this control phase and the switchover solenoid valves (y18 and y19) closed. The pressure occurring between the high pressure/return pump (p1) and the switchover solenoid valve (y18) is reduced by the pressure limiting valve integrated in the switchover solenoid valve.
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P42.35-0211-76
ETS control mode pressure reduction
The control process or valve positions shown in the example relate to the VR brake when a calculated brake pressure of > 60 bar is reached in the brake caliper.
a Suction line
e duced pressure
f High pressure
If the brake pressure to prevent acceleration slip is too high, the ETS control mode pressure reduction starts.
When a calculated pressure of > 60 bar is reached in the brake caliper the pressure reduction phase is introduced by actuation (opening) of the solenoid valve. Solenoid valve (y8) remains closed. The brake fluid flowing back flows partly through the inlet solenoid valve (y22), partly via the high pressure/return pump (p1) and the pressure limiting valve integrated in the switchover solenoid valve (y18) via the brake master cylinder back to the brake fluid reservoir.
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When a calculated pressure of 60 bar is reached in the brake caliper the pressure reduction phase is introduced by opening of the switchover solenoid valve (y18). Solenoid valve (y8) remains open and solenoid valve (y9) remains closed.
The brake fluid flowing back flows via the high pressure/return pump (p1) through the switchover solenoid valve (y18) via the brake master cylinder back to the brake fluid reservoir
The self-priming high pressure/return pump (p1) is also actuated in these control phases.
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P42.35-0213-76
ETS control mode pressure increase at a rear wheel (HR)
a Suction line
f High pressure
P42.35-0214-76
ETS control mode pressure increase at both rear wheels
a Suction line
f High pressure
P42.35-0215-76
ETS control mode pressure increase at both rear wheels and one front wheel (VL)
a Suction line
f High pressure
P42.35-0216-76
ETS control mode pressure increase HL and pressure holding HR and VL
(Example: Calculated brake pressure in the VL brake caliper < 60 bar)
a Suction line
b Brake pressure
f High pressure
P42.35-0217-76
ETS control mode pressure increase HL, pressure reduction HR and pressure
holding VL
(Example: Calculated brake pressure in brake caliper < 60 bar)
a Suction line
b Brake pressure
e Reduced pressure
f High pressure
Referenced documents
- gf4235p3000a ETS, ABS control mode, function
- gf4235p4000a Arrangement/purpose/design/function of ETS hydraulic unit
- gf4235p4500a Location/purpose/design/function of ETS control module