When Safety Standards Demand Dual Redundant Hoist Brakes
Welcome to the Hoist Guy's blog! In this post, we discuss different types of hoist brakes and the special feature of dual redundant braking, required by some applications where safety is key.
by Andrew T. Litecky on October 31, 2016
A customer recently asked us: Could you give us some insight into the difference between hoists with both mechanical load brakes and motor brakes versus hoists with only a single motor brake?
To start with, all electric hoists on the American market are built with a motor brake. These brakes by design are magnetically spring loaded and referred to as "fail safe." In the event of the loss of power or when the hoist operator releases either the up or down push button, the electromagnets release the brake and the springs set the brake. The brake manufacturer sizes the brake according to torque and the hoist manufacturer chooses the correct brake per the hoist motor horsepower. Some hoist manufacturers build their own motor brakes and some buy a motor brake from an outside source.
A mechanical load brake, also known as Weston type mechanical load brake, is by definition a mechanically operated brake, located in an oil bath. Its purpose is to act as a secondary brake, in case of catastrophic motor brake failure. While the hoist load is lowered, it also assists the hoist motor in controlling the load against the force of gravity. It does this by absorbing energy and dissipating this energy in the form of heat, in the oil bath. This is why a hoist gear case will feel hot during operation. Some hoist manufacturers offer the mechanical load brake as standard equipment, while others offer it as an option. And some do not offer it at all.
For most applications, a single brake meets all safety needs. However, some end users insist on "dual redundant holding brakes." This can be accomplished by using either a hoist with a motor brake and a mechanical load brake or a hoist with dual motor brakes. Either way, dual redundant brakes ensure maximum safety by providing a secondary braking system should the primary brake fail. This is an important consideration for applications with critical lifts over processes or operations where a motor brake failure would have catastrophic consequences.
At Shupper-Brickle, our years of experience in overhead material handling offer a unique expertise in the industry. Besides offering a wide range of brands, our in-house engineering team offers custom solutions. Contact us about your specialized application or heightened safety standards.