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.
Motor: Stall Current
Motor: Off Load Speed
Gearbox: Gear Ratio
Motor: Stall Torque
Motor: Off Load Current
4 miles with 15AH batteries
4mph (with standard controller)
18 stone person (Robot Wars weight
limit is approx. 12.5 stones)
2x 12V 38AH
The motor and gearbox are about 28cm long
Front of the motor, and fixing to frame
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
Gearbox and wheel
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).