Product category:
Springs, dampers, latches, locks and small components
News Release from: Rencol Tolerance Rings | Subject: Tolerance rings
Edited by the Engineeringtalk Editorial
Team on 10 May 2005
Tolerance rings oust clutches in SUV
applications
Tolerance rings offer an appealing alternative to conventional clutches in the retraction mechanisms of sports utility vehicle running boards.
SUVs often incorporate running boards to allow ease of access The boards are typically designed so that they operate automatically when a door is opened, with self-retracting mechanisms so that they do not present a hazard during driving
This article was originally published on Engineeringtalk on 25 Jul 2008 at 8.00am (UK)
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Although such designs offer benefits for vehicle owners and indeed, other road users, they also potentially place the retraction mechanism at risk from damage.
In the event of the vehicle passing over an obstruction the motor or operating mechanism could be easily damaged.
In order to protect the motor, it is usual to incorporate a clutch mechanism to enable the drive gear to slip when an obstruction is encountered.
But conventional clutches are relatively heavy and bulky, and so vehicle manufacturers are now finding that use of a tolerance ring provides a much simpler and cheaper means of providing overload protection.
Tolerance rings are circular spring steel fasteners used to joint annular components.
They have waveforms around their circumference which form a robust friction fit between mating surfaces.
Although the rings can be designed to create an immoveable joint, they can also be engineered to slip within precise torque parameters.
Reports Chris Needes of Rencol Tolerance Rings: "A traditional clutch used in a running board application would normally be about 14in diameter, using space and adding weight to the vehicle".
"The tolerance rings used are typically around 16mm diameter and perhaps 20mm deep".
"Introduced between the motor and drive gear they can be designed to slip at 60 to 70Nm so that the running board is not forced into any obstacle and the motor is not overloaded".
"The ring will then operate normally, providing a secure connection once the obstruction is removed".
"Thousands of slip cycles can be accommodated without impairing performance".
In volume production, tolerance rings, although generally purpose-designed for each application, can cost just a few pence each, making them a markedly less expensive alternative, while providing greater durability than the more traditional clutch mechanisms. Request a free brochure from Rencol Tolerance Rings ...
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