[freebeard]

Originally Posted by redpoint5

Curious how pushing a button (or other activation method) is more convenient than pressing the brake? How does hill hold do a better job than the brake?

If modern hill holders have a button it's a different thing. In 1950 it was a checkvalve in the brake line that held pressure if the vehicle was pointed uphill. No need to heel-and-toe.

Originally Posted by [URL="https://en.wikipedia.org/wiki/Hill-holder"

en.wikipedia.org/wiki/Hill-holder[/URL]]
Hill-Holder is a name for the mechanism invented by Wagner Electric and manufactured by Bendix Brake Company in South Bend, Indiana. Studebaker[1] 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. In modern usage, this driver-assistance system is also called hill hold control (HHC) or hill start assist (HAC).

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.