A hand operated lift in a explosive chamber is required as shown in Figure 1. The load to be lifted may range from 200 to 1800 lbs. The lift distance is 3 inches and the pipe is 3 ft long. The Takeup Drum is twice the diameter of the pipe.
The items to be designed or selected include:
- Pipe size ( Schedule 40 Pipe)
- Cable size
- Gear sizes ( 4 gears )
- Inside Ratchet Design
The lever with ratchet is 2 ft long and can be moved through an 18 inch arc length each stroke. The operator can apply a 10 lb force to the lever. Lower operator load is desirable.
The number of lever strokes should be minimized for all load ranges.
The customer also desires the pipe diameter to be small because of the cost to drill the hole. The customer also would like rope diameter to be small and the ratchet thickness to be small in order to minimize the internal protrusion of the drum and ratchet into the inside chamber.
A conceptual ratchet is shown in Figure 2. The gear (1) has a number of triangular teeth that are held in place by a spring loaded pawl (2). Both parts are pin mounted to a base (3).
For this design the number of teeth and depth of teeth need be chosen. Considerations include the turn angle for each stroke, the bearing stress on the teeth and pins and shear stress on the teeth.
Attachment:- MECH_Solution.zip