Customized Bridge Crane with Movable End Stops
Andrew T. Litecky
Welcome to The Hoist Guy's Blog, where our resident hoist guy, Andrew T. Litecky, shares his industry knowledge and experience. In this case study, we solve a customer’s overhead lifting challenge with a customized solution to flexibly or temporarily restrict trolley movement in certain areas.
Case Study: Can you flexibly restrict trolley travel on certain areas of a bridge crane runway?
A customer purchased an underhung bridge crane with a 5-ton capacity, 20-ft span, and CMAA Class C rating, along with an ACCO Work Rated monorail wire rope hoist. The runway was 100 ft long and ran the length of the building. The customer’s special request was to restrict trolley movement in certain areas along the runway with the flexibility to easily remove that restriction when needed.
The Customer’s Unique Overhead Lifting Challenge
On one side of the runway, sensitive pressure vessels extended for 20 feet along the side of and 5 feet away from a wall. So, while the overhead lifting system was designed for hoist movement on the entire 100 feet length, a hoist carrying the finished product was never allowed to travel next to the pressure vessels. However, in certain cases and when not carrying product, the hoist needed access to the restricted area for maintenance of the pressure vessels.
Our Solution for Flexibly Restricting Travel on a Span
Our solution to restrict a hoist from a part of the runway on a temporary basis was to design, test and install mid-span, movable end stops that automatically lowered and raised when needed. The stops were designed to stand up to daily usage for general production, but also movable when needed for equipment maintenance.
What are Bridge Crane End Stops?
End stops are a fixture on a bridge, runway or monorail to keep the trolley hoist from running off the end of the beam. They’re typically a permanent part of the overhead lifting system and usually bolted in place.
When the need for maintenance arises, the trolley hoist may be moved outside of the normal operating area, often by removing an end stop. However, the process to remove a typical end stop can be arduous.
Removing Bridge Crane End Stops
To remove a permanent end stop, a technician must use a scissor lift or ladder to unbolt the stop and allow the trolley hoist to pass. Later, when the work is done, the trolley hoist must pass through the stop area again. The end stop must be reinstalled, again with the use of a scissor lift or ladder. If maintenance is performed multiple times in a week, month or year, this becomes a time-consuming process.
To avoid this long process, we designed a system of powered stops to save both time and money.
How Do Movable End Stops Operate?
Moveable mid-span stops can be controlled in a variety of ways: by a travel limit switch, a PLC, or manually by a hand-held pendant that’s wired to a wall mounted controller. The pendant can operate on 115V-1-60 power, plugging into a standard receptacle. The stops are powered by a linear actuator with a 2” stroke and exerting 112 pounds of force.
When activated, the stops prevent trolley movement on both sides of the beam flange. They pivot on a bolt and work as a pair on either side of the flange. The powered stops raise and lower instantly with no need for disassembly, and the frame work and actuator are located above the top flange of the beam. Movable mid-span end stops can be customized for the height of the beam section.
Other Uses for Movable End Stops on a Crane
Moveable mid-span stops are not just for stopping trolley hoists on monorails, but they’re useful to limit the travel of any trolley or underhung bridge crane on a runway. Meanwhile, they might also be used with an overhead trolley-mounted door to permit that door to stay open or closed.
The above drawing shows the general arrangement of the stops on a runway system.
Custom Engineering for Overhead Material Handling
Shupper-Brickle combines over 50 years of hoist and crane industry experience with a full-service engineering department to offer a range of customized crane and material handling services. We have experience engineering custom solutions for unusual and unique overhead lifting applications. Contact us for more information on our custom crane and material handling engineering services including complete analysis and custom design of overhead material handling systems.
