Maintenance Fundamentals Episode 1 part 10 pdf

Mechanical Flexing

Mechanical-flexing couplings provide a flexible connection by permitting the

coupling components to move or slide relative to each other. To permit

such movement, clearance must be provided within specified limits. It is import￾ant to keep cross loading on the connected shafts at a minimum. This is

accomplished by providing adequate lubrication to reduce wear on the coupling

components. The most popular of the mechanical-flexing type are the chain and

gear couplings.

Chain Chain couplings provide a good means of transmitting proportionately

high torque at low speeds. Minor shaft misalignment is compensated for by

means of clearances between the chain and sprocket teeth and the clearance that

exists within the chain itself.

Figure 10.2 Typical split rigid coupling.

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174 Maintenance Fundamentals

The design consists of two hubs with sprocket teeth connected by a chain of the

single-roller, double-roller, or silent type. A typical example of a chain coupling

is illustrated in Figure 10.4.

Special-purpose components may be specified when enhanced flexibility and

reduced wear are required. Hardened sprocket teeth, special tooth design, and

barrel-shaped rollers are available for special needs. Light-duty drives are some￾times supplied with non-metallic chains on which no lubrication should be used.

Gear Gear couplings are capable of transmitting proportionately high torque at

both high and low speeds. The most common type of gear coupling consists of

two identical hubs with external gear teeth and a sleeve, or cover, with matching

internal gear teeth. Torque is transmitted through the gear teeth, whereas the

necessary sliding action and ability for slight adjustments in position comes from

a certain freedom of action provided between the two sets of teeth.

Slight shaft misalignment is compensated for by the clearance between the

matching gear teeth. However, any degree of misalignment decreases the useful

life of the coupling and may cause damage to other machine-train components

such as bearings. A typical example of a gear-tooth coupling is illustrated in

Figure 10.5.

Figure 10.3 Typical compression rigid coupling.

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