Research Project Information

Research Project Summary Information

Torque Limiting Clutch for 4WD/AWD Vehicles(ST9396-1)

New Process Gear (Division of Magna Powe


Many four-wheel drive (4WD) and all-wheel drive (AWD) drivetrains in light-duty highway vehicles use clutch mechanisms that are actively controlled to modulate the amount of torque transferred to downstream driveline components. The active clutch will transfer torque up to a preset limit, beyond which it slips. Since spike loads are absorbed by the clutch, downstream components such as shafts and gears can be made smaller and lighter, and fuel economy will rise due to two factors: (1) the vehicle weighs less and thus requires less energy to accelerate to a given speed, and (2) because a large portion of the mass reduction occurs in components that rotate, less energy is needed to overcome the inertia of these parts as they are spun up to required speed. Unfortunately, active torque transfer systems are expensive, primarily because of the cost of the actuation system and the electronic control module that senses vehicle conditions and sends commands to the actuation system. Unless the active system is also used to implement some other function, such as automatic stability control as offered on certain premium vehicles, the vehicle designer is likely to use a simpler, inexpensive clutch that requires downstream components to be stronger, heavier and less fuel efficient.

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Project Description

A proposed solution is to package a friction-slip type torque limiter into a transfer case or axle drive. Two proposed design concepts include: two cone clutches with friction interfaces at the inner and outer cone surface, and a multi-plate wet clutch. These designs are adaptations from existing clutches used in industrial machines. In each concept, the torque limit is set at or slightly above the skid torque of the application. In the event that slip occurs across the clutch, the slip speed would be monitored and controlled by adjusting the output torque of the vehicle’s engine, thus protecting the clutch from overheating. The required control features would be integrated into the existing drivetrain control module. The work in this project entailed designing, building and testing prototypes, and working with customers to validate the designs in vehicles.


This concept could reduce the fuel consumption and exhaust emissions of 4WD and AWD vehicles, and has the potential to create New York jobs associated with building drivetrain components.

Project Results

New Process Gear executed this project and intended to manufacture and sell the resulting products. A severe downturn in the market for 4WD and AWD products at the time this project was completed caused all production plans to be put on indefinite hold.


New Process Gear (Division of Magna Powe
6600 New Venture Gear Dr. Attn: Anthony Benenati
East Syracuse, NY 13057

Principle Investigator

Sankar Mohan

Universities Involved


Project Type:

Product Development

Technologies Types:

Light Duty

NYSERDA Contact Information

Joseph Wagner


R&D -Transport & Power Systems

Contract Details

Start Date: 1/11/2010
Project Status: Active
Contract Number: ST9396-1

Last Updated: 3/28/2013