Thursday, July 30, 2009

Caster Mounting - Part 1 - Grip Ring Stems

The grip ring stem is quite possibly the most common caster stem in use. Used predominately on consumer and commercial office and shop equipment, this stem provides rapid installation and quick change. Grip ring stems are typically available on furniture and institutional casters.

The stem works by utilizing a piece of round steel with a channel machined in the top portion. The machined channel is then fitted with a locking ring, either brass or steel. This ring is slightly larger than the stem itself. The mounting sockets are made to match the stem, with a recessed race in the top portion of the socket, so as to accept the locking ring from the stem. When inserted the locking ring expands into the recessed race, locking the stem into position. The mechanism provides positive retention, without impeding removal should it be required.

Grip ring stems are most commonly used on molded plastic components, wherein the socket can be made an integral part of the equipment. This reduces overall cost and makes for faster manufacturing.

These stems can also be used in equipment made of round or square hollow tube. Pre-sized sockets are available for common mill sizes. Socket inserts are quite inexpensive and provide an easy and simple way to make equipment mobile that otherwise would not be.

There are some noted disadvantages of using a grip ring stem caster. Capacity being the first. Generally speaking, 200-lbs is about the limit of a grip ring stem. This is in part due to the nature of the casters it is sold with, and that it is a narrow distribution of the load. The load being focused on the kingpin entirely. Secondly, over time, it is possible for grip ring stem casters to come loose. So these are not generally indicated for abusive or rough applications.

All in all, the grip ring stem provides a great solution for many mobility applications. Its rapid installation and change-out, high availability, and the variety of casters fitted with grip ring stems, make it a tempting choice for designing a mobile product.

If you have questions regarding your mounting options, please contact us.

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