Retractable Docking Pin

Download Design Files and Bracket STLs Here 

This is the retractable docking pin that I designed to dock my V6 Frontier wheelchair in my van.  I need a docking pin that retracts because fixed docking pins kill the ground clearance and hit the ground and door thresholds. Now I can go offroad over rocks without worry.

I designed the retractable docking pin in Fusion 360. It uses a small actuator with a 2" stroke to extend or retract a 8 inch bolt through a round tube. I designed brackets to be 3d printed for mounting the actuator. Dad welded the steel tube to the angle and I 3d printed the brackets.  The bolt locks into an EZ Lock or QLK docking system.

The wheelchair batteries are 24 volt and the actuator is 12 volts so I used 100 ohm resistors to reduce the voltage. I picked resistor values that match the motor impedance, which cuts the voltage in half.  I used resistors instead of a DC converter because the DC converters constantly draw a quiescent current which will drain the battery over time. By putting the resistors on the load side of the switch, there is no quiescent current.

The cost of the materials for this retractable docking pin was just $145, which was several thousand dollars cheaper than what the wheelchair company was charging.

This docking pin was designed for the Frontier V6 power wheelchair by Magic Mobility but it can be adapted to fit other chairs.