TORNADO - The Team with the Comedy Flying Cow
THE WHEELCHAIR

This is the wheelchair we bought back in April 1999, and which we intially intended to base our robot on. Back then the team and robot were called Plague, and we had little idea of how much things would change...
We sold the wheelchair onto a team from Bradford in January 2000, when we decided it wasn't going to do what we wanted it to.

Specifications
Supplier
Make/Model
Voltage
Range
Speed
Carrying Capacity

Supplied Batteries
Motor: Stall Current
Motor: Off Load Speed
Gearbox: Gear Ratio
Motor: Stall Torque
Motor: Off Load Current
SCL Mobility
Cruiser 2E
24V
4 miles with 15AH batteries
4mph (with standard controller)
18 stone person (Robot Wars weight
   limit is approx. 12.5 stones)
2x 12V 38AH
105A
3520 rpm
32:1
7.52Nm
1A
Roadblock, winner of Series 1 and Series 2 finalist, is actually based on a very similar chair, just cut down with road signs over the top. The large batteries in the photo are not the originals - they were totally shot. New front castors were fitted not long before we bought it. The gearboxes had a lever enabling them to be disengaged, so the chair could be pushed manually. It had a horn, and electronic brakes that hold the chair when stationary.

More Photos

The motor and gearbox are about 28cm long

Front of the motor, and fixing to frame

The wheels...

The front of the controller

The two batteries...

The wheel, motor and lower frame

The battery box (2 black things) and footrests

...are 12" (30cm) diameter.

The rear of the controller, key in ignition

...are 38AH capacity.

The batteries in the cradle

The joystick control

Front view

Gearbox and wheel

Back view

Gearbox

What did we do to it?
We built the wooden battery cradle, charged and wired up the batteries, and run and tested the chair. It could pull my Dad's Escort van with the standard controller. We also dismantled the gearbox and looked at the gears - the smallest looked about 1.25mod, the rest bigger than 2mod, and they appeared to be barely worn.

What's was good about it?
It was cheap, all in one robot solution. For better performance, it could have easily been made to run with a mechanical (relay) stepped speed controller. The torque at the wheel could have been considered to be better than a Bosch motor - when geared for a typical 10mph at 24V (12" wheel), the Bosch gives 165Nm - the wheelchair has 240Nm. For a Bosch to produce the same wheel torque, it must be geared for 7mph. The data for both motors is included in our motors spreadsheet - download it to see what they can do.

What's was wrong with it?
It was sold by SCL because part of the frame got broken (the lady who owned it before was rather large apparently) - they could have got the part (it would only have cost them 15) but it took several months to get, and it is was not worth it taking up their limited workshop space for that time. SCL brazed the frame so the chair would hold a person, but they didn't recommend someone using it without it being fixed properly (welded or replaced).

Also the batteries were not in great condition, although fine for testing, and it's top speed was a little low by Robot Wars standards.


| Home || Build Diary || Official Merchandise || Site Map || E-Mail |