Tuossa vähän infoa:
Transmissions with the kickdown inhibitor include the AW 71 L combined with the B 230 FT engine (Europe), the AW 71 with the B 280 E and B 280 F (excl. USA/Canada) and the AW 72 L (excl. USA/Canada). The kickdown inhibitor has two functions, both of which are designed to avoid overrunning of the engine:
A shift from 3rd to 4th takes place even if the accelerator is held in the kickdown position when accelerating to an extremely high speed.
Downshifting to 3rd is prevented above a certain speed even if the accelerator is pressed to the kickdown position.
The kickdown inhibitor is controlled by signals from the speedometer and from an oil pressure switch (26) which, in turn, is actuated by the throttle pressure/kickdown pressure in the control system. The signals are fed to the solenoid valve (25) via the relay and then to downshift valve 4-3 (18). See also hydraulic circuit diagrams in Control system .
Principle of operation
The control system prevents the downshift valve from downshifting from 4th to 3rd at speeds above 120 km/h. However, this may be overridden in the kickdown position with the aid of the kickdown inhibitor, permitting a shift to take place up to approx. 160 km/h.
60-120 km/h (37-100 mph):
Under normal driving conditions, the shift valve controls the shifting speed, which may vary depending on the throttle opening (throttle pressure).
60-160 km/h (37-74 mph) + kickdown:
At full throttle, the throttle pressure becomes kickdown pressure, enabling the oil pressure switch on the gearbox to operate the overdrive relay. If the speed is below 160 km/h, the relay will close the solenoid valve which actuates downshift valve 4-3, permitting a downshift even if the speed exceeds 120 km/h.
Above 160 km/h (100 mph):
At approx. 160 km/h, the relay is operated by the signal from the speedometer. The solenoid valve is energized and upshifting takes place.
If the accelerator is inadvertently moved to the kickdown position at a speed above 160 km/h, downshifting will occur since the speed at which this is performed by the downshift valve is exceeded, while the relay is blocked by the speedometer signal and cannot actuate the solenoid valve.
To avoid unnecessary solenoid valve wear, it is not operated by the relay at low speeds (below approx. 80 km/h = 50 mph) at which the kickdown function is activated by the downshift valve.
Neither the shift/downshift function (performed with the button on the gear selector lever) nor the operation of the indicating lamp is affected by the speed or kickdown pressure. These function in the same manner as before.
