I think you need to reconsider your design. When you mentioned that motor earlier, I thought maybe it was for a model, not a full sized wheelchair. Will you be using two motors or just one?will this circuit work because there will be a lot of weight on the motor ?? and is there a formula of finding the power of motor by the weight ?i am using a 150watt power motor the weight on the motor is about 120 Kgs is the motor ok ?