| The tank uses two AMD D-Pack electric motors, one for each side. The motors can draw well over 100A each, and will produce over 1 Hp each. Here the motor is mouned on an adjustable swing arm to set the belt tension. | |
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Here's a view of both motors installed before the frame
was put into the body. This was my first attempt at a drive
reduction. It failed because no matter how much I tightened
the
belts, the second stage would slip. |
| This is the current (final?) design. It uses three stages for an overall reduction of about 57:1. The ratios are 4:1, 35:11, and 9:2. The large pully is 6" in diameter, and I used number 35 chain. |  |
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This
is
the view from the front. The final drive shaft is 3/4", and
the
others are 5/8". The vendor sent me the wrong part for the
first
chain sprocket which had a 1/2" bore instead of 5/8", so I had to turn
the shaft down on my lathe. The final and intermediate shafts are nicely ground and keyed (expensive) and are mouned on ball bearings in wood pillow blocks. I used wood because at the time I only had a wood lathe. The first shaft is mounted on ball bearings in aluminum blocks, which I fashioned with my mini-mill and mini-lathe. Projects like this are great excuses to get cool tools. The shaft is cheap 5/8" hot rolled stock from Lowes, which I turned to size and keyed. |
| Each drive shaft has a sprocket that engages the track.
The sprocket is made from two plywood gears mounted on a
pipe-flange hub. The hub is a short length of iron pipe with
a
pipe flange welded on each end and is keyed to fit the shaft. The hubs broke and required repair. I used a 2" piece of 3/16" steel to engage the key in the shaft, but the steel pipe deformed under the load, breaking the weld. The pieces were reworked with a 4" length and more metal on the weld. |
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While I had it apart for repairs, I thought I would paint it. You can see the cut aways in the gears for the track link screws. I chucked an end-mill bit in my drill press and used a jig with a pin to fashion the pieces. |