Identifying Non-Inversions of Double Slider Crank Chain

A double slider crank chain is a kinematic chain with four lower pairs, specifically two turning (revolute) pairs and two sliding (prismatic) pairs. Its inversions are formed by fixing different links of the chain.

Mechanism Analysis

Let's examine the given options in the context of the double slider crank chain and its inversions:

• Oldham's coupling: This mechanism is a classic example derived from the first inversion of the double slider crank chain. It is used for connecting two parallel shafts, allowing for some misalignment and transmitting rotation.
• Pendulum pump: This type of pump is typically driven by a pendulum motion or oscillation. It is generally associated with single slider crank mechanisms or other oscillating systems, not directly with the inversions of a double slider crank chain.
• Scotch yoke mechanism: This is a well-known application of the first inversion of the double slider crank chain. It converts rotary motion into simple harmonic linear motion.
• Elliptical trammels: This mechanism, used for drawing ellipses, is also derived from the double slider crank chain (specifically, its first inversion). It consists of two sliders moving in perpendicular guides.

Conclusion on Inversions

Based on the analysis, Oldham's coupling, the Scotch yoke mechanism, and elliptical trammels are all derived from or are inversions of the double slider crank chain. The pendulum pump does not fit this classification.

Therefore, the mechanism that is NOT an inversion of the double slider crank chain is the pendulum pump.