Designers: Andrew Lokker, Garrick Tolley, Max Kellish
Supervising Professor: Larry Bohs
Figure 1. Trike Tote
INTRODUCTION
Our client enjoys riding his customized Harley trike, but needs to attach his wheelchair to the back of his vehicle before riding. The Trike Tote provides him with an easy, secure, and adjustable method for attaching his wheelchair. While seated on the vehicle, picks his chair up from the ground, places the axle bar into the ratcheting grips on top of the box, and then rotates the chair until the bar underneath the seat of the wheelchair locks into the flexible marine spring clips oriented on the custom clamps. With the Trike Tote, the client can securely mount his wheelchair to the trike in under a minute.
SUMMARY OF IMPACT
Prior to the development of our device, the process of loading or unloading the client’s wheelchair onto the trike required around 10 minutes and at least five bungee cords. The Trike Tote allows himto easily load and unload his chair in 28.1 seconds and 37.6 seconds respectively, while also providing a stable and secure attachment mechanism. The finished project also includes space for a storage box on the back of the trike. The client is satisfied with not only the ease of use and security of attachment but also the universal and minimalist design. NEED A CLIENT QUOTE.
TECHNICAL DESCRIPTION
The Trike Tote (Fig. 1) is made up of seven main components: an aluminum tubing base, four flanged clamps, four two-way connector clamps, two ratcheting Rhino Grips, a telescoping tubing mechanism, two custom clamps with marine clips, and a wheel mount. The aluminum base consists of round 6061-T6 aluminum bare drawn tubing (0.75” inner diameter, 1” outer diameter), cut into three pieces (two running parallel to the trike and another that acts as a crosspiece). This general frame provides the structural support for the wheelchair’s attachment points.
The two lengthwise aluminum base pieces are correctly oriented and aligned to the box using four commercial flanged clamps (manufacturer, model 1” diameter with a base of 2.05” x 2.09”) that are tightened around the two ends of each piece. To allow these flanged clamps to be welded to the storage box, … These flanged clamps are each secured to an aluminum piece (2.05” x 2.09” x 0.25”) using four screws; all four square pieces have been welded to the top of the box to ensure correct positioning. This ensures both a secure and stable connection between the device and the storage box, and allows for the attachment system to be removed from the top of the storage box if the user wishes to do so.
Four round aluminum two-way connector clamps (1” diameter at both connection points) connect the attachment features to the base frame and provide universal design. Two connector clamps connect the parallel lengthwise frame pieces with the crosspiece on which the Rhino Grips are mounted; the other two connector clamps attach each of these lengthwise pieces to the telescoping tubing mechanism that houses the passive clamping mechanism for the bar underneath the wheelchair’s seat. Horizontal adjustability is achieved by untightening these clamps using a hex key and sliding the pieces forward and backward along the stabilized parallel frame pieces. The Rhino Grips are a commercial product sold by Kolpin Powersports. These are made from hard industrial grade plastic and are lined with soft rubber. These firmly grip the axle bar and bear the majority of the weight of the chair. They are attached to the top of the crosspiece of the base aluminum frame using four screws and corresponding nylon nuts. A thin layer of rubber is positioned at the interface of the grips and the crossframe to reduce friction.
The telescoping tubing mechanism consists of three separate pieces fit together. Two pieces of round 2024-T3 aluminum bare drawn tubing (0.76” inner diameter, 1” outer diameter) have been cut (7.75’’ long), attached to a two-way connector clamp at one end, and positioned vertically. Starting from the topmost end, five 0.25” holes were drilled in each pipe at inch long increments. The inner telescoping piece is constructed from round 6061-T6 aluminum bare drawn tubing (0.50” inner diameter, 0.75” outer diameter). Two vertical pieces (7.25’’ long) have been welded to a crossing rod (9’’ long) to create an inverted U-shaped bar that serves as the attachment point for the custom clamps. Only one 0.25” hole is drilled into each vertical piece of the inner telescoping component, which allows five different height levels to be reached for a high level of vertical adjustability. A preferred height can be secured and locked using two correspondingly sized nuts and bolts to connect the inner and outer pieces.
The custom clamps were machined from two blocks of 6061-T6 aluminum. Each clamp consists of two halves that perfectly tighten and fit around the 0.75” diameter of the inner telescoping piece, and they are secured together using ¼-20 screws that fit through a clearance hole in the top half and thread into a tapped portion in the bottom half. A plastic 1” diameter marine spring clip is attached to the top of each clamp using two 10-32 screws. These clips work as passive clamping elements that secure the bar underneath the wheelchair’s seat. The custom clamps can also be rotated 360 degrees to account for any angle that the bar will load into the clips as a result of rotation.
The wheel mount is an optional piece that is a repurposed axle from a recycled wheelchair. It can be clamped to the two lengthwise aluminum frame pieces in the space between the Rhino Grips and the telescoping mechanism. If the client wishes to ride with a passenger, the wheels may be removed from the chair and the axle pins of each wheel fitted into the wheel mount on the device, thus storing the wheels. This frees up space on the bike that would otherwise be taken up by the wheels when attached to the chair, giving the owner the ability to ride with a passenger. Figure 2 shows the client using the Trike Tote. The cost for the components of the device is approximately $450.
Figure 2. Client using the Trike Tote