Hill-holder

Any device that prevents a car from rolling backward on a hill when the brake pedal is released can be called a hill holder. The earliest hill holders were used in horse-drawn carriages and early horseless carriages. They were often home-made or made by a local blacksmith. These early hill holders were little more than a heavy iron weight with a spike or other sharp end that could be quickly dropped behind a wheel when the need arose, preventing the vehicle from rolling backward.

Hill-Holder is a name for the mechanism invented by Wagner Electric and manufactured by Bendix Brake Company in South Bend, Indiana. Studebaker and many other carmakers offered the device as either optional or standard equipment for many years. It is a device that holds the brake until the clutch is at the friction point, making it easier to start up hills from a stop in manual transmission automobiles. It was first introduced in 1936 as an option for the Studebaker President. By 1937 the device, called "NoRoL" by Bendix, was available on Hudson, Nash and many other cars. Another name for the mechanism is a hill hold control (HHC).

Availability

As a trade name, it was introduced by Studebaker in the 1936 President. It was also promoted by Studebaker as an option in the 1939 model year. Later, it was available on older Subarus, and is currently available on the Subaru Forester, Subaru Impreza and Subaru Legacy The 2009 Dodge Challenger SRT8 also comes equipped with hill-holder. Hill-holder works by holding the brake in position while the driver sets-up and activates the first gear to move the car forward from a complete stop, without fear of roll-back.

Similar systems are or were in use by Alfa Romeo, Citroën, Fiat (including the new Fiat 500), BMW, Skoda Superb 2009, Lancia, Mercedes-Benz, Volkswagen, Lamborghini Aventador, Saab, smart ("Hill Start Assist"), Subaru, Cadillac ("NoRol") and Stutz ("Noback").

The mechanism was available in American car parts stores so that car owners could add to their vehicle to improve it from the late 1930s through the 1950s. But it required that the car have hydraulic brakes, so it could not be added to Ford Motor Company products before 1939. In 1949 it became available on factory-built Fords. GM would not follow suit until the 2012 Chevrolet Sonic.

Cars with Hill-holder feature:

Make	Model	Year	Comment	Reference
Subaru	Outback	2003-Current??		above
Subaru	Impreza	2003		above
Subaru	Legacy	1989-Current?		above
Dodge	Challenger SRT8	2009
Fiat	500 Sport	2011
Chevrolet	Sonic	2012
Honda	CR-Z	2012	Called "Hill Start Assist"
Honda	Fit and Fit Hybrid	2014?? (NOT 2013)
Chevrolet	Spark	2013	Called "Hill Start Assist"
Mercedes-Benz Smart	ForTwo	2011	Called "Hill Start Assist"
Mercedes-Benz	GL320	2008
Mercedes-Benz	M-Class	2012
Volkswagen	Passat	2012
Audi	A3	2012
Kia	Soul	2012
BMW	5-Series	2012
Mahindra	E2O	2013	electric car

Operation

In layman’s terms, the modern hill-holder function works by using two sensors, in concert with the brake system on the vehicle. The first sensor measures the forward-facing incline (nose higher than tail) of the vehicle, while the second is a disengaging mechanism. The 1930s-1950s NoRoL used a ball bearing as a check valve in the hydraulic brake line; when the car was on an uphill incline, the ball rolled back and blocked the brake line - when the car was level or facing downhill, the ball rolled away, leaving the line free. The clutch linkage slightly dislodged the ball when the clutch was released, enabling the car to move away from a stop.

Manual transmission vehicles

When the driver stops the vehicle on an incline where the nose of the car is sufficiently higher than the rear of the car, the system is engaged when the driver's foot is depressing the brake pedal, and then the clutch pedal is fully depressed. Once set, the driver must keep the clutch pedal fully depressed but may remove the foot from the brake pedal. To disengage the system and move the car forward, the driver selects first gear, gently depresses the fuel pedal, and slowly releases the clutch pedal which at a point in its travel releases the braking system, allowing the car to proceed.

Usage

Hill-holder works best for those who are inexperienced with manual shift techniques, or in situations with heavy traffic in steep hilly conditions (as in San Francisco, or Duluth for example).

However the same technique can be accomplished by a driver through the use of the manual parking brake lever, coordinated with the brake, clutch, gear shift and accelerator. This is a standard technique in most countries where manual transmissions remain popular, for example the UK. Cars equipped with a parking brake pedal are not suited for this maneuver unless it is released by hand, for example in the Citroen XM.