Welcome to The Hoist Guy's Blog, where our resident Hoist Guy, Andrew T. Litecky, shares his knowledge and experience of many years in the overhead material handling industry to talk about overhead bridge crane trolley travel limit switches.
Why do you need a trolley travel limit switch for your overhead bridge crane?
The short answer is to ensure the safety of your bridge crane, you need a trolley travel limit switch.
What’s a trolley travel limit switch?
Trolley or bridge travel limit switches are safety devices used to prevent the motorized trolley or bridge from striking the end stops of the monorail, crane or runway at a high speed. Cases of high impact collision of the trolley against the end stops can lead to the damage of equipment or materials and even personnel fatalities.
The trolley travel limit switch is activated by a trigger. The trigger is clamped to the top flange of the monorail or crane beam, and an arm extends into the path of the trolley. When the trolley hits the trigger, the limit switch functions to slow or stop the motorized trolley. Limit switches are designed for adjustability, so the stopping distance can be determined and changed if needed. Stopping distances vary with trolley or bridge speeds and loads.
How do trolley travel limit switches save money and ensure safety?
1. By preventing damage to the system
A key safety benefit of the trolley or bridge travel limit switch is that it prevents the operator from inadvertently moving the trolley or bridge against the end stop and then keeping the button depressed. In this case, the wheels continue to turn, damaging both the beam flange and the drive wheels. For extra high speeds, travel limit switches can be setup in two stages: a slowdown and a complete stop. This gives the operator more flexibility in the stopping point.
2. By preventing damage from swing loads
Slamming into an end stop at high speed, especially with a fully loaded trolley hoist, will cause the trolley or bridge to stop abruptly and the load to swing. In a tight working area, this adds stress to the hoisting equipment and can damage the surroundings (for example, if a wide load that extends past the end of the bridge comes in contact with a conduit or process piping). Also, chances are increased of dropping a full load.
3. By ensuring the safety of the operator and other personnel
A distracted operator moving a loaded crane is an accident waiting to happen, and workplace fatalities have been recorded for this reason. Travel limits add an extra layer of protection for the operator and bystanders, stopping the movement of the trolley and bridge before anything catastrophic can happen.
How do I get a trolley travel limit switch?
Trolley and bridge travel limit switches are an added feature for most brands of cranes. For some imported brands, especially by European manufacturers, limit switches are standard. For American-made overhead bridge cranes and crane kits, travel limit switches are an added option. Over time, the return on investment will more than pay for itself with reduced wear on equipment and increased personnel safety.
Contact Shupper-Brickle Equipment to add a trolley travel limit switch to your overhead system. With over 50 years in the business, we know cranes. Ask us about new equipment, field service, and overhead crane engineering.