Requirements for LifeTrac Wheel Motors and Couplings

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Status: provisional/incomplete. See discussion for required actions.

Please maintain the distinction between requirements - things to achieve - which should be on this page, and designs or design specs - things to have or ways to achieve or do things - which should be elsewhere. Link them in if relevant.

Notes for Designers

Please model your design as fully as is feasible. The best design will have the best evidence that it meets all the requirements and has the best trade-offs in all areas.

Please share any solution models (eg: FEAs) you use including original files and summary reports in standard formats.

Please share general modelling of the problem domain - loads, statistical models, etc, so that the entire community can refine its understanding of the problem.

If you think any part of the spec is unreasonable, unclear, or missing or incomplete, please tell us. Help us to refine it.

If you can't model, or can't meet any part of the spec, please say so, and please share your designs anyway. Anything is better than nothing, and other people may be able to build on your work.

Functional Requirements


At least two wheels must be driven by hydraulic motors. At least four wheels must be mounted. All wheel drive is highly desirable. Suggested motor for AWD is XXXX(link).


The mount - motor - coupler assembly must be fabricated simply, using only a minimum of special purpose components. In addition to the hydraulic motors, bearings, standard fasteners (nuts, bolts, etc), XXXX, sheet plate tube and bar steel are allowable. Cutting (Flame, Plasma, abrasive), drilling, punching, XXXX, and welding (Oxy Torch) are allowable.

Other components and processes will be considered, but are discouraged.

Bolt together assembly should be used where possible to facilitate repair and component upgrade or reuse.

Quick change mounts

Bolt or other temporary fixing must be used for attachment to the LifeTrac frame.

Quick change mounting between the motor-coupler assembly and the frame is highly desirable, to reduce MTTR and allow easy modular repairs with few tools.


Solution must be robust

All aspects of the LifeTrac must be long lasting and reliable under intended, and reasonably anticipated but unintended, uses.

Typical Load

Torque: Motors will often be operated at maximum rated torque. Design for a duty cycle of 50%, with one reversal every 3s.

Weight supported by the four wheels will be XXXXkg total, including LifeTrac, X powercubes (at the back), and XXXXkg on the loader.

Vibration: When driven on rough ground, additional cyclic loads of 0.8G @ 15Hz will be applied.

Impact Load

Should survive driving over a sharp a drop of 15