Project Overview
This lifting frame was designed and manufactured by Rope and Marine to aid with the replacement of door motors from Bakerloo line trains during repair works. The purpose was to eliminate the need for any manual handling of the motors. Due to their low position in the carriage, previously, operators had to bend down in an unsafe position that could cause injury to their backs when lifting the motors.
Design and Engineering
The design needed to be as light as possible for ease of use, while still maintaining enough strength to lift the weight of the motor. The frame works by latching onto the carriage handlebars and the foot plate rests against the seat frame. The crane arm features a retractable and extendable rubber buffer that pushes against the window of the carriage to secure the device in place. After design revisions, a torque limiting device was added to ensure the buffer would not exert excessive force on the glass and potentially damage it.
Manufacture and Assembly
Thin steel square hollow section made up the majority of the frame’s structure, with plates being precision cut on our CNC plasma cutter. All metal parts were welded by our coded welders in our workshop. The frame also featured bespoke plastic parts that were 3D printed from PLA using our own 3D printer. Due to eight frames being ordered and the large number of parts in each frame, assembly took a significant amount of time and required precision to ensure all moving parts worked smoothly together.
Testing and Implementation
Both simulations and physical load testing were conducted on prototype models to ensure the frame was fit for purpose and could withstand wear and tear over time in service. Extensive onsite testing was carried out to make sure the frame could work in multiple use cases with different door layouts. Training of how to use the motor lifting frames was conducted by RAMS staff on site at the depot to ensure all operators were comfortable using the device.
Outcomes and Lessons Learned
The lifting frame successfully met all design and performance criteria, significantly improving the safety and efficiency of the door motor replacement process. Operators reported that the device was easy to handle and greatly reduced the physical strain previously associated with the task. Feedback from the client was highly positive, particularly regarding the frame’s lightweight design and secure locking mechanism.
