We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is the Stall Torque?

By N. Kalu
Updated May 17, 2024
Our promise to you
About Mechanics is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At About Mechanics, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

Stall torque refers to the torque of a device when that device's rotational speed reaches zero. It can also refer to the torque load needed to cause the device's rotational speed to drop to zero. A motor stall torque is equal to the motor's maximum torque, which is usually zero revolutions per minute.

Devices that produce this sort of torque include electrical motors, steam engines, and hydrodynamic transmissions. For electrical motors, torque can still be measured even when these motors are stalled. Maximum continuous stall torque refers to the greatest amount of torque that a stalled motor can provide without overheating or causing damage to itself.

Hydrodynamic devices such as a fluid coupling, a device used to move mechanical power from one step to the next, can also produce a stall torque. This device's torque corresponds to the maximum amount of torque it can produce without breaking or damaging. Measuring torque while the unit is stalled is the best way to gather accurate information.

Various types of torque converters have measurable stall torques as well. For these devices, the stall torque is greater than or equal to the maximum output torque for a given input speed. The industry standard by which all other converters are judged is the Borg Warner torque converter, designed by a fluid dynamicist from General Motors. The Borg Warner converter is considered the standard because of its unique qualities while stalled, including its resistance to moving around in stall mode.

A torque converter multiplies the stall torque ratio of a normal torque device. It is used to move vehicles with automatic transmissions by allowing the engine to spin without being tied to the transmission. Torque multiplication from a converter is dependent upon four factors: the size and shape of the turbine, and the size and shape of the stator blades. Typical ratios for automotive purposes range from 1.8:1 to 2.5:1.

Torque is also related to a rotational device's revolutions per minute (rpm). At zero torque, the maximum rpm can be reached. Maximum rpm occurs when the motor is not under any specific load, such as an automobile frame or a large conveyor. In this case, the rpm is referred to as free rpm. The formula which relates these different factors is: T = Ts - (N Ts ÷ Nf) where T equals the torque at N rpm, Ts equals stall torque, and Nf equals the free rpm.

About Mechanics is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.

About Mechanics, in your inbox

Our latest articles, guides, and more, delivered daily.