Gears and Four-Bars

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Gears and Four-Bars

Geared Four-Bar Mechanisms

Geared Four-bar Mechanisms are usually built with:

A four-bar mechanism, with at least one Part that rotates continuously

One or two Gear-Pairs

The input 'drive' gear is fixed to the Coupler, at the distal end of the Crank or Rocker

The output gear is usually at the ground joint of the respective Crank or Rocker

'Geared Four-Bar Mechanisms' are often used as 'Function-Generators'. Function-Generators provide an input to output motion relationship.

Typically, the input to these mechanisms is a continuously rotating Crank.

Typical Geared Four-bar Mechanism Configurations

One Gear-Pair

Regressive and Ir-regressive Gears

I have no idea why they are called 'regressive' and 'ir-regressive' gears!

Regressive gears are at each end of the Crank,

Ir-regressive gears are at each end of the Rocker.

tog_minus'Regressive' Geared Four-bar

tog_minus'Ir-regressive' Geared Four-bar

Two Gear-Pairs

Usually, the two gears on the same shaft at the are edited so that they have the same module and number-of-teeth. Although, this is not necessary.

There is a small complexity in MechDesigner (special rule) that means you must use a 'trick' when you add the second Gear-Pair.

tog_minus'Three Geared Drive'