Do FisherPrice Gearbox Documents Exist?

Technical Motors
1

I am unable to find any documentation for the FP Gearbox included with the KoP that would answer the following questions

  1. What is the gear reduction of the Kit of Parts Fisher Price gearbox?
  2. What is the maximum output torque of the KoP Fisher Price gearbox?
  3. The “Where to Get More” document doesnt list this this part. Where do I get more?

It looks like we’ll be trying to figure out questions 1 and 2 when we meet tomorrow as was done in the this thread but actual specs from a document would be nice also.

2

Count the number of teeth on each gear, and calculate each stage’s ratio as a ratio of tooth count. For example, if the first gear has 25 teeth and the second gear has 75 teeth, the ratio is 25:75, or 1:3. Three turns of the first gear results in 1 turn of the second gear. If on the second gear there is a third gear of 30 teeth, meshing with a 4th gear of 70 teeth, the ratio is 30:70, or 3:7. If you go from the first gear to the 4th gear, the ratio is 3:21 (=1:7), where 7 turns of the first gear results in 1 turn of the 4th gear.

3

While I don’t have the exact number, you’ll smoke the FP motor before the gearbox fails.

4

JVN is always your #1 friend. :slight_smile:

JVN’s Mechanical Design Calculator

5

We used a FP gearbox / motor last year to power our winch. We made many lifts during practice and compentition and never had any trouble

6

A little counting and some math.

The FP Motor has a 19T Pinion on it. The FP Gearbox internally is made up of multiple compound gears.

Pinion Gear 19T
Compound Gear 1 (72T Large / 25T Small)
Compound Gear 2 (79T Large / 14T Small)
Compound Gear 3 (45T Large / 12T Small)
Final Gear (38T Large) Connected as a Compound Gear to the Spindle

19T/72T x 20770 = 6008.75RPM
25T/79T x 6008.75 = 1901.50RPM
14T/45T X 1901.50RPM = 591.58RPM
12T/38T X 591.58 = 186.82RPM AT THE DRIVEN SPINDLE.

7

Be aware that there are many different versions of the F-P gearbox. The one from the 2011 KOP was one that I’d never seen before, with a differently-shaped black case, and orange slotted output hub.

Old information may well refer to a different version that was not provided in the KOP this year.

Getting more has historically been a bit of a pain with F-P parts. The Power Wheels service centres have been ordered not to sell some parts to the general public, presumably for fear of the electrical parts being installed incorrectly. This applies specifically to the motors, but since the gearbox and motor are usually found together, it can complicate matters.

8

I pulled this year’s gearbox apart to get those numbers I posted above.

9

With these numbers and the addition of efficiency calculated in, I came up with a few more specs.

95% X 3 stages + 90% X one stage with funky bearings = 77% efficiency.
34.4 Ft. Lbs of usable torque, or, 47.7 N m.

10

I get 5481 rpm at the first stage for a total of about 170 rpm. Is the math wrong or did the gear get reported incorrectly?

11

We counted 78T on the large gear. I know one tooth won’t change the calculations by much, but the engineer in me likes precision so I was wondering if anyone else has confirmed the Alienvin’s tooth counts. We confirm the counts of all the other gears.

12

Anyone know where to get more? I’d like to have an identical spare.