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Dismantling Mirage Wheelchair Motor Gearbox

Posted: Tue Jan 02, 2018 5:33 pm
by admintrev
I replaced the motor/gearbox units when they started making horrible noises.
I decided to dismantle the gearbox units and replace the bearings to see if that fixed the issue.
gearbox_housing_small.jpg (46.92 KiB) Viewed 26 times

input_shaft_bits_small.jpg (18.6 KiB) Viewed 26 times

main_shaft_bits_small.jpg (23.63 KiB) Viewed 26 times

main_shaft_bits2_small.jpg (25.56 KiB) Viewed 26 times

misc_bits_small.jpg (30.31 KiB) Viewed 26 times

secondary_shaft_bits_small.jpg (24.44 KiB) Viewed 26 times

US6029763-2.png (54.32 KiB) Viewed 26 times

The above drawings show the gearbox unit after dismantling, the last image shows the constructional detail from US Patent 6029763
I managed to dismantle the gearbox without damaging any of the parts, with the exception of slight damage to the plastic on the input shaft bearing and I needed to drill holes in the main shaft oil seal, screw in self tapping screws so that it could be pried out.
I will be purchasing replacement bearings along with the mains shaft oil seal, the parts should be available from most bearing supply companies,
the part numbers of the original parts are as follows:
6904 RS, 6003 2RS, 6200 2RS, 6200 2RS, 6001 LU and TC 20 37 8 (known as 20x37x8mm Nitrile Rubber Rotary Shaft Oil Seal with Garter Spring R23 / TC)
Hopefully this information will be helpful to anyone else who wishes to dismantle one of these gearboxes.

Re: Dismantling Mirage Wheelchair Motor Gearbox

Posted: Tue Jan 02, 2018 10:00 pm
by admintrev
Regarding the bearing part numbers, I've had a look online and found the following:

Part Number, Bore Dia, Outer Dia, Width
6904 = 20 mm, 37 mm, 9 mm
6001 = 12 mm, 28 mm, 8 mm
6003 = 17 mm, 35 mm, 10 mm
6200 = 10 mm, 30 mm, 9 mm

The letters and numbers after the part numbers describe the seals.
RS means a rubber seal on one side, LU also means a rubber seal on one side.
All the bearings have rubber seals on both sides, so the part numbers to order should be either 2RS or LLU (depending on make) to mean rubber seals on both sides.
e.g. 6001 LLU = 6001 2RS.

The breakdown of the part number for the shaft oil seal (TC 20 37 8) is:
TC = Double lip (sometimes R23 is used)
20 = Bore Dia (mm)
37 = Outside Dia (mm)
8 = Width (mm)