Application of the Month
Ship Shape Material Handling
March, 2008 - View all Application Examples
Material handling applications come in a wide variety of design concepts. Moving goods from one location to another can present some unique challenges, especially when done at sea.
A customer recently came to us with a difficult requirement for a gearbox to drive a winch that could transport supplies between ships at sea. Several important parameters put our design team to the test.
The first parameter was one of space. The entire winch drive had to fit within the tower structure elevating from the ship’s deck. With an existing structural design, the winch wheel, driving gearbox, and large motor, had to fit within a very confined envelope. With height readily available, but width at a premium, a right angle solution was the only choice.
However, most helical bevel designs, the preferred choice, and worm designs as well, have their inputs at the centerline of the gearbox. While normally not a problem, in this case the larger width of the motor would interfere with the inside of the tower structure. The overall length from the outer edge of the winch wheel to the outer edge of the motor casting was just too much.
The unique solution we were able to offer was our Watt Drive “Series C” helical bevel gearbox. This design has an offset input stage that allows the motor to be rotated off center to one of all four sides. This configuration was originally designed to allow close mounting of the gearbox to a frame, such as for wheel drives or other applications where the load needs to be mounted as close to the gearbox as possible. This was the perfect solution for this challenge as the motor could be oriented below the winch wheel with plenty of clearance within the tower structure.
The second major parameter was the ability of the gearbox to handle shock, not only in the gearing, but in the housing and mounting flanges as well. Potential concussion shocks or tower torsion could not compromise the integrity of the drive.
The normal cast iron material used in our standard drives was deemed too brittle to withstand the unusually high level of shock forces that were specified as a requirement. To satisfy this demand, we identified a special ductile iron that had the proper elasticity characteristics. To produce these castings, new molds would be required. But alternative solution costs justified the added expense to meet these strict requirements.
The third major parameter was for adequate radial load capacity on the output shaft, where the winch wheel was attached. While normal operating loads were to be limited to a specific value, emergency loads of double the value were possible. For added security, a safety factor of 2.5 was specified to accommodate a catastrophic occurrence.
To handle this requirement, a special bearing box adapter was designed to fit inside the winch wheel to better center the load over bearings and reduce the effect of the cantilevered design. Calculations were performed, based on expected operating times and potential overloads, to select the appropriate bearings necessary to handle the task with plenty of safety.
The fourth parameter was to offer a motor with brake to handle all the above parameters of shock and load, along with being able to withstand the various environmental conditions that could be experienced. This could include everything from arctic conditions to the high heat and humidity of the tropics.
While Watt Drive doesn’t provide this kind of motor, a partner company with experience in custom military applications does. A customized solution was offered that allowed for the option of simple electrical control, or the possibility of more complex electronically controlled operation.
After several months of discussion and design, the result was a gearbox and motor combination that satisfied the strict and demanding requirements, specifications, and envelope limitations.
While most material handling applications can be satisfied with our more standard products, DieQua has the ability and know-how to offer customized solutions for the unique requirements that are often necessary. While most manufacturers shy away from these challenges, especially in smaller quantities, we find these types of applications to be extremely interesting. They also allow us to use our consultative approach to help our customers come up with unique solutions, which sets them apart from their competitors.
Whether you have a standard application or one that requires some creativity, Diequa Corporation has a wide range of gear drive solutions suitable for virtually every industry engaging in rotary motion. Give us a call next time you have a tough problem to solve. We like those best.
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