Removable chain hoist position encoder assembly

Abstract

A chain hoist having a casing into which and with respect to which a chain travels is provided with an externally mounted position encoder assembly. A releasable connector, such as a ratchet strap, is employed to firmly but removably couple the position encoder assembly housing externally on the chain hoist casing. The releasable connector holds the position encoder assembly housing in a fixed position relative to the chain hoist casing. The position encoder assembly has a chain gear that is rotatably mounted relative to the position encoder assembly housing proximate to the chain access opening in the chain hoist casing. The precision encoder assembly chain gear engages the portion of the chain that is maintained under tension at a location externally of the chain hoist casing and rotates as the chain travels relative to the chain hoist casing. A releasable clamp is anchored relative to the position encoder assembly housing and is engageable to maintain engagement of the position encoder assembly chain gear with the chain. An encoder is mounted with respect to the position encoder assembly housing and detects rotational movement of the position encoder assembly chain gear. The sensor provides electrical output signals indicative of the extent and direction of rotational movement of the position encoder assembly chain gear. The position encoder assembly provides precise, reliable output signals indicative of the position of the chain relative to the chain hoist. The position encoder assembly may be readily removed from the chain hoist, and just as easily attached thereto.