Mounting cranes on rails increases their utility in loading/unloading and other material handling tasks. However, it also creates another potential hazard: the risk of uncontrolled movement. Tall cranes used outdoors, especially in coastal regions, are vulnerable to high winds and wind microbursts. Earthquakes are another possible cause of unexpected motion in many locations, and the risk of collision with forklift trucks and similar machinery is ever-present throughout industrial and logistics operations.
Uncontrolled crane movement can be devastating, as is evident in a 2008 video of a crane collapse in Florida. It can disrupt operations, require expensive repairs and even cause loss of life. This is why storm and parking brakes should be considered essential on rail-mounted equipment. Here we explain these, outline how the various types work, and discuss when each should be used.
Rail Clamps and Wheel Brakes
Storm and parking brakes for rail-mounted equipment act either on the rail or on the wheels. The two categories are rail clamps and wheel brakes.
As the name suggests, clamps clamp onto the rail. This makes them appropriate for static situations where they act as parking brakes. In contrast, wheel brakes apply friction to the wheel (usually the idler wheels of cranes.) Thus, while wheel brakes are intended for static use, they can be used as dynamic brakes in emergencies.
Rail clamps come in two forms: clamps that grip onto the sides of the rail and press brakes that push down on the top. Clamp mechanisms usually include rollers that run along the tops of the rails. Retractable systems are available for high-speed cranes where rollers would add additional resistance.
Press brakes use the crane’s weight to lock it in position while clamps rely on spring force (which can exceed 1,000 kN.) Press brakes are used where the rail top is flush with the roadway and inaccessible to side clamps. They also do a better job of accommodating variation in rail height.
Brake Application and Release
Rail clamps, rail press brakes, and wheel brakes are all designed for fail-safe operation. Spring-loaded mechanisms force the clamps or friction material against the rail or wheel. Then, power is applied to pull the clamps off.
With clamps and press brakes, the release is almost always performed by hydraulics. (Some smaller units have electric release mechanisms.) Likewise, wheel brakes are predominantly electric release. However, hydraulic systems are more complex, requiring a pump or pumps plus reservoir, and should be inspected for leaks periodically.
When selecting or specifying storm and parking brakes, remember to consider how they are released in the event of a power failure. Again, the manufacturers or a knowledgeable distributor will be able to advise.
Partner With Specialists
As safety-critical components, it’s essential to use only the correct storm and parking brake systems and components for your application. Kor-Pak works with multiple manufacturers and can advise on the various types and styles. Replacement parts and servicing are also available. Contact us for more information.