Parallel Planetary gear box

Background:  The PowerQuick ascender uses a planetary gear box for driving a rope capstan.  The gear box has a reduction of 40:1.  A hardened steel input shaft that is approximately 6 inches long has a 5/8 inch diameter and terminates in the input pinion for the first stage.  On the input end, there is an integral brake housing.  The output is a .750 diameter shaft with a 3/16 keyway. 

The gear box is a two stage machine with a NEMA 34 mounting configuration.  The body of the gear box must be constrained to a square 3.250 inches on a side.  Length is optional; however, the desired length from the mounting face to the end of the ring gear is less than 4.0 inches.

Cost is a driving requirement.  Gear ratios in the range of 30:1 to 50:1 are acceptable.  Unlike most planetary gear boxes, backlash is desirable as opposed to minimized.  With the loose backlash, providers are encouraged to use low cost manufacturing techniques.  Costs should be stated for production quantities of 10 and 100 per month.

Requirements:

1. Two-stage planetary gear box.
2. NEMA 34 mounting.
3. Corrosion resistant finish, either stainless steel or zinc coated.
4. Performance:
   1. Average dynamic torque-                      1,250 inch-pound
   2. Max Dynamic torque-                           1,800 inch-pound
   3. Max Static back drive                           6,000 inch-pound
5. Life at average load 200,000 rotations
6. Speed at input                                                  1,600 RPM
7. Speed at output                                                     40 RPM
8. Back drive torque-no load                                   <50 inch-pound
9. Output shaft                                                      .750 dia. X 1.5 with .188 keyway.