science

Hill-holder

Hill-holder is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Hill-holder rather than just read about it. In short: A hill-holder is a motor vehicle device that holds the brake until the clutch is at the friction point, making it easier for a stationary vehicle to start uphill. By holding the brake in position while the vehicle is put into gear, it prevents rollback.

Key takeaways

Hill-holder belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Hill-holder to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Hill-holder from memory before moving on to harder problems.

Reference excerpt

A hill-holder is a motor vehicle device that holds the brake until the clutch is at the friction point, making it easier for a stationary vehicle to start uphill. By holding the brake in position while the vehicle is put into gear, it prevents rollback. The hill-holder was invented by Wagner Electric and manufactured by Bendix Brake Company in South Bend, Indiana. 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. Studebaker and many other carmakers offered the device as either optional or standard equipment for many years. In modern usage, this driver-assistance system is also called hill-hold control (HHC), hill-start assist (HSA) or hill-start assist control (HAC).

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, the technology became available on a variety of modern automobiles, starting with the 2005-onwards Volkswagen Passat, 2011-onwards Volkswagen Jetta, and 2004-onwards Volkswagen Phaeton and Touareg. It is further available on the Subaru Forester, Subaru Impreza and Subaru Legacy. The 2009 Dodge Challenger SRT8 also comes equipped with hill-holder. Similar systems are or were in use by Alfa Romeo, Citroën, Fiat (including the new Fiat 500), BMW, Škoda Superb 2009, Lancia, Mercedes-Benz, Volkswagen, Lamborghini Aventador, Saab, Smart ("Hill Start Assist"), Subaru. Pre-WWII Cadillac ("NoRol") and Stutz ("Noback") were offered with the technology as an option. 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.

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 gas pedal, and slowly releases the clutch pedal which at a point in its travel releases the braking system, allowing the car to proceed.

Automatic transmission vehicles In an automatic transmission vehicle, the car is equipped with a tilt sensor that, when it reaches a certain angle or greater, tells the brake system to keep the brakes clamped for a few seconds longer after the driver releases the brake. This allows time for the driver to depress the accelerator, moving the vehicle forward.

Usage Hill-holders work 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 Citroën XM.

References

Illustrations

Worked examples

Example 1 — a first encounter with Hill-holder

Start with the simplest possible case. Write down what Hill-holder claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Hill-holder before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Hill-holder ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Hill-holder

In research: Hill-holder appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Hill-holder in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Hill-holder is common in secondary-school and first-year university syllabi. It links to neighbouring topics Advanced driver assistance systems, Automobile transmissions, Automotive technology tradenames, so understanding it makes those chapters shorter.
In everyday life: Look for Hill-holder outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Hill-holder in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Hill-holder means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Hill-holder out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Hill-holder in simple terms?

Why does Hill-holder matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Hill-holder?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Hill-holder.