Slip Rings Ring Rotary Electrical Joint Collector Electric Swivel Electromechanical Airflyte Electronics

1. Low speed: 250 feet per minute maximum
2. High speed: 5,000 feet per minute maximum

For low speeds a wire type wiper made out of a precious metal alloy (gold, platinum, silver, copper, nickel) can be used if the current is less than 5 amperes maximum. For other speeds, the use of silver graphite material is required (80% silver, 15% C, 5% MoS2). At surface speeds over 250 feet per minute, without the benefit of lubrication, metal to metal contact will result in rapid deterioration of the surface by galling or seizing. The addition of graphite or MoS2 to silver, plus water vapor normally present in the atmosphere will impart the lubricity needed at the interface of the brush and ring as one slides relative to the other. For surface speeds above 5,000 feet per minute, special consideration must be given to lubrication, cooling and ring-brush material combination. At altitudes above 60,000 feet with its concomitant low atmospheric pressure, the water vapor present is so minimal that most silver graphite brushes dust and deteriorate rapidly and other approaches must be considered.

The wear factor is slip ring design is all important because the useful life of the unit depends upon it. The result of wear is deterioration of the surface which results in an unacceptable noise pattern. The mechanism of wear is based on the following parameters:

Under normal conditions, because of the metallurgical properties of the alloys in contact, lubrication is not necessary. However, for unusual applications, such as high vacuum, it is considered good design to supply either sacrificial or boundary lubrication.

The general configuration of slip rings can take either one of two shapes: Disc or Cylinder. In either instance, it must be realized that there are dissimilar materials involved in a design, all of which have different properties especially at elevated temperatures. These materials might be:

Since many assemblies are purchased as complete units, it is important to understand the basic construction. Because of the many environmental conditions encountered, it is found that the bearing are of great importance. The bearings nearest the support is usually fixed, while the other bearing is retained on the outer race only. In this manner, allowance can be made for expansion or contraction and even some minor misalignment without subjecting the assembly to undue stress. Driving should always be accomplished by means of a flexible coupling to avoid unnecessary strains on the bearings.

In general, it may be assumed that the co-efficient of dynamic friction is approximately .2\ and the coefficient of static friction is approximately .3. In the event that the surface of the ring is V-shaped, then all values must be multiplied by 1.414 to compensate for the double contact.