A clean brake for mining

Hilliard A400 caliper brake.

Australian Mining breaks down the various mining applications of The Hilliard Corporation’s BrakeBoss hydraulic control system.

Braking systems are essential to the safe and efficient operation of a slew of mining machines. Everything from draglines and shovels to grinding mills, railcar dumpers and positioners benefit from high-quality braking applications.

The Hilliard Corporation has released a series of brakes that integrate with the company’s BrakeBoss control systems. The power units are designed to accommodate a variety of braking applications.

The BrakeBoss line is split into four models, the BBH1, BBH2, BBH3 and BBH4 power unit, which provide a wide degree of versatility when considering the required level of brake controls.

“When designing brakes, Hilliard listens to the voice of the customer, taking suggestions on features and benefits and incorporating them into the standard product designs,” a spokesperson from The Hillard Corporation tells Australian Mining.

“Fewer spare parts and parts commonality allows users to keep minimal parts inventory, while also allowing Hilliard to keep on-hand inventory for immediate delivery.”

BBH1, the base BrakeBoss model, comes with simple on/off and ramped braking options. The simplest of the four models, it is well suited for rail car dumpers, crane hoists and overland conveyors.

BBH2 adds torque controls via an engineered hydraulic circuit for extra versatility and is useful for overland and underground conveyors. It is also equipped with manual overrides and a hand pump to allow brake operation during a power outage.

The BBH3 power unit adds more advanced control options, including the capability to continually adjust brake pressure following a preselected profile (“closed-loop” brake control).

The BBH4 power unit, meanwhile, is designed for brakes with pressures above 3,000 pounds per square inch (207 bar).

The inside of a BrakeBoss BBH3 unit.

High-capacity, semi-autonomous grinding (SAG) mills, which are driven by gearless mill drives requiring powerful spring-applied hydraulic brakes to stop mills from rotating in cases of emergency or power failure, are well suited for this power unit.

Hilliard’s safety systems for its brakes incorporate a maintenance mode allowing users to lock the brake off in place. The systems also monitor pad wear to notify the operator that pads need to be changed or air gaps need to be adjusted.

“Hilliard brakes have been designed to make maintenance as simple as possible, which helps in personnel safety,” the spokesperson says. Hilliard’s spring-applied M900SH brake caliper has been tested in extreme environments for hardiness. It uses a floating design that accommodates 20 millimetres of axial movement to compensate for thermal expansion of mills caused by high operating temperatures.

The calipers apply controlled braking applications to stop the mill when it is rotating at full speed – such as in an emergency stop scenario – or quick applications to stop the mill during inching, creeping and in instances of power failure.

For dumpers and positioners designed to unload ore from rail cars or barge unloaders, Hilliard’s A300- T300SH arm-style caliper offers two stages of hydraulics when combined with BrakeBoss – a lower torque setting for emergency stopping (to minimise cable stress) and a higher torque setting for parking.

The design of the A300 also allows for a fast conversion between rightand left-handed calipers. Draglines and shovels also benefit from the use of the spring-applied braking systems by using Hilliard’s A400-T300SA and A400-T400SA pneumatic release braking systems, in place of drum and plate brakes of diameters above 610 millimetres.

These systems achieve full brake retraction using less than 90psi (6.2 bar) of air pressure and are available in two sizes to accommodate disc thicknesses of 25 and 38 millimetres, respectively.

The brakes are generally placed at the three o’clock and nine o’clock positions to prevent thrusters from pulling on the caliper arms and cause one pad to drag on the disc.

“By keeping the brakes equally spaced around the brake disc allows for even heating and cooling of the brake disc,” the spokesperson adds. “If the application doesn’t allow for the mounting in those positions, Hilliard has an adjustment mechanism as a standard feature on the caliper to compensate for the mounting.”

This article appears in the May 2019 issue of Australian Mining.

To keep up to date with Australian Mining, subscribe to our free email newsletters delivered straight to your inbox. Click here.