Will Hill Holder reduces the fear of driver while climbing hill?
Driving a car at hill stations, especially while going up, what will be you think? The only thing in our minds is to safely moves the vehicle forward from an initial position without going down. Why may this happen? While driving on plains roads, the center of gravity (CG) of the car is acting towards the ground, and also it is located at the center, which is perpendicular to the vehicle and road surface too. So the vehicle can't move in such directions, we can drive a car just like that. While driving on sloping roads, the CG of the car is acting towards the ground only, but the car is in the inclined position on slopes. So the location of CG is in the rear while moving up, and the CG is in front while moving down. That's why the vehicle moves down while starting from an initial position. For these difficulties, engineers built a logical device named No Roll. Also, it has pronounced as Hill Hold Control or Hill Hold Assistance or Hill Holder.
Hill Holder's construction and design are varied for manual and automatic transmission systems. In a manual transmission system, there was a mechanical setup between the master cylinder and brake lines. This setup consists of a cam and ball mechanism. The cam has connected with the clutch wire, and the ball is for opening and closing the fluid passage. Before moving the car uphill from stationary, the clutch has disengaged for setting first gear, and the brake is applied. While disengaging the clutch (pressing the clutch pedal), the cam moves towards the ball and tries to close the brake fluid passage by pushing a ball. When we release the brake pedal, the fluid can't return to the master cylinder because, due to CG, the ball moves towards the passage and stops the fluid flow. Then by engaging the clutch (releasing the clutch pedal), the cam pulls the ball gradually, so the fluid lines become open. So by concurrently giving the acceleration, the car moves forward without slipping down. This mechanism occurs only in sloping conditions.
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| No Rol mechanism |
For an automatic transmission, the setup is entirely different from the above. It consists of a hydraulic modular unit, which is also used in ABS and ESP systems, that optimizes the fluid pressure on each wheel, and a control unit is used to governs the entire operation. Before moving the car uphill from stationary, we apply the brake on the wheels to avoid roll down. At the time, the control unit fetches data about the fluid pressure built up on brake lines using a hydraulic modular unit and holds that built pressure steadily even we release the brake pedal and retentive the pressure for few seconds for acceleration. While we accelerate the vehicle, the modular unit releases the pressure on brake lines, so the car moves forward without rolling down. We can turn off this control system if not required (i.e.,) in plains roads we need not turn on this system. Overall this hill-hold assistance holds the brakes for a few seconds to prepare the driver for moving forward by avoiding roll-back.
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