Brake linkage bushings improve park braking
11 August 2023

A large freight-rail operator in Australia has approved Vesconite Hilube brake linkage bushings for its locomotive fleet, to replace bushings in its fleet’s brake levers and improve its park brake performance.

Brake linkage bushings are essential to brake rigging systems, which distribute braking forces from the brake cylinder to the various wheels using rods and levers linked with pins and bushings.

“The Australian company was looking for three different bushings from a self-lubricating material able to withstand high loads,” describes Vesconite Rail COO Zané Easton.

“Reduced wear and the ability to withstand high loads are critical for brake linkage bushings in the rail industry,” she notes.

Vesconite and the Australian company first began to discuss bushing materials in 2019.

In May 2021, the conversation became more focused on the brake linkage bushings’ specifications.

Two months later, an initial set of Vesconite Hilube bushings was installed on a locomotive for on-track testing.

Subsequent monitoring showed that the Vesconite Hilube bushings demonstrated minimal wear during each inspection.

Metallic and nylon brake linkage bushings have proved inadequate by past users and have been associated with a lack of park brake force and unfortunate incidents involving brake failure.

The metallic brake linkage bushings tend to exhibit excessive wear, leading to the horizontal and vertical misalignment of the top lever with the brake cylinder and, consequent, brake failure.

Nylon brake linkage bushings, meanwhile, soften in humid conditions, which can lead to loss of compressive strength and creep ⎻ and lessen the effectiveness of a locomotive’s braking system.

“Increasing the efficiency of the brake system without changing the brake rigging design can be accomplished by using our self-lubricating bushings with a low coefficient of friction to limit the frictional losses in the system,” Easton states.

She says that rolling stock operators have used Vesconite Hilube bushings to reduce wear, improve braking efficiency, decrease maintenance costs, and prevent brake seizures since the material does not swell and has a low thermal expansion.

Railway procurement managers were also encouraged to buy Vesconite Hilube because of the shorter lead times when ordering Vesconite materials.

However, the deciding factor in choosing the more efficient brake rigging system bushings, which can operate at a 1:40 gradient, was a requirement to reduce mechanical losses in the system. This ties in with the desire of the rail industry to increase safety and to prevent infrastructure damage, including to derailed container wagons, train tracks and overhead power lines.

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