Cognate Linkages

Cognate linkages

Cognate linkages Hartenberg and Denavit suggested the term

cognate" to describe those linkages that trace the same coupler curve. There are three cognate 4-bar,,toeach of which there corresponds a cognate 5-bar ,of a total of six linkages that trace identical coupler curves.

A 4-bar mechanism (MQ 4-bar)

Pivot triangle MQO similar to coupler triangle ABC

with side MQ corresponding to side AB. The cognate 4-bar having crank pivots Q and O is referred to as QO 4-bar.

The QO 4-bar

The coupler triangle for the QO 4-bar must be

similar to the pivot triangle. The side DC of the coupler triangle corresponds to QM of the pivot triangle. Triangle DCE similar to triangle QMO.

The OM 4-bar

GF of the coupler triangle corresponds to MO the

pivot triangle. Triangle GFC similar to triangle MOQ

The MQ 5-bar

The cognate 5-bar linkage corresponding to the

MQ 4-bar will be called the MQ 5-bar.

The OM 5-bar

The QO 5 -bar

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