Pedal power on the railway

This amazing pedal car for a quarry railway was in the museum at Penryn Castle. One detail is hard to see in the photographs of the back of the carriage. Each of the 4 foot cranks from the front is connected to the drive shaft at 90 degrees to the others. This means that there will always be drive from one of the shafts and enough momentum to push the opposite shaft back into position. It's a bit like a 4-cylinder engine.