The Official Mert's Hands Website

Instruction and User Guide

Thank you for selecting the Lawwill Quick Release prosthetic hand attachment. During eight years of extensive research and development, this device has been tested in many different situations.

Proper adjustment is necessary for the device to work as designed. What follows are some brief and general instructions for installation and adjustment for optimal performance.

While installation is not difficult or laborious, if you are not a competent mechanic it is in your best interest to have a professional mechanic make some of the modifications / conversions for you.

Please note that, because instillation instructions vary by type of motorcycle, some personal modifications not listed below might be necessary to make the conversions to your specific machine. Also, if you devise some way other than those listed below to convert your machine (e.g. special brackets, special levers etc.) please share this information with your fellow amputees so that they can benefit from your ingenuity

Converting Your Machine

If you are a left amputee, you will need the clutch lever relocated to the right handlebar. If the clutch is mechanical (cable) this is best accomplished by placing the lever slightly below the front brake lever (the front brake lever can be raised slightly to aid placement as long as it can be reached effectively while riding).

If the clutch is hydraulic the lever can not be inverted, as is necessitated by relocation of the stock lever below the front brake lever, so installation is best accomplished by positioning the lever on the back side of the handlebar (facing the rider) so that it can be depressed with the thumb (sometimes this necessitates the fabrication of a bracket specific to the motorcycle). For both the mechanical and the hydraulic clutch, a longer cable/line might be required.

If you are a right amputee, you will need the throttle and the front brake lever repositioned to the left handlebar. Repositioning the throttle shouldn’t necessitate any special parts, with the possible exception of a longer throttle cable. If the front brake is mechanical (cable) repositioning it to the left handlebar simply requires remounting it above the clutch lever (or beneath, if you prefer). If the brake is hydraulic the lever cannot be inverted, as is necessitated by relocation of the stock lever above the clutch lever, so installation is best accomplished by positioning the lever on the back side of the handlebar (facing the rider) so that it can be depressed with the thumb (sometimes this necessitates the fabrication of a bracket specific to the motorcycle). For both mechanical and hydraulic brakes, a longer cable/line might be required.

Adjusting the Device

As you can see, the device is comprised of a ball on the end of the prosthesis and a socket mounted on the handlebar. The device releases the ball from the socket when the force applied by the ball to the socket exceeds the threshold of the detent plunger set by the user. This threshold is modulated by setting the detent springs in the socket, and by varying the length of the shaft of the ball. When adjusting the detent springs keep in mind that they should be at least tight enough to avoid any up-and-down free play, but not so tight as to create drag on the assembly. Although release pressure can be modulated by tightening/loosening these detent screws (turn them outward for easier release), it is recommended for best performance that at least three of them be engaged at all times to full pressure. Be sure to keep them clean and lightly lubricated to ensure they work effectively.

There are two shaft lengths on the balls provided. The short shaft will allow a decreased range of motion before the device releases, and the long shaft will allow a greater range of motion. Choose which shaft length works best for your type of riding and riding style. For example, motocross and dirt riders will be best served by the longer shaft, as the greater range of motion allowed by it will permit them to stand up without the device releasing, while casual riders or road racers would be well served by the shorter shaft, as the decreased range of motion.