GRV-1 Turbotug Project 11/27/04

Posted on November 27, 2004

       With a few days off of work I was able to find time to visit the garage and work on the Turbotug. Some critical systems were yet to be built so I was busy brainstorming on what to tackle next.  One concern that I had about my design is the safety of the driver. With the engine transversely mounted, I had to devise a secondary scatter shield to ensure that a turbine failure could not send shrapnel toward the driver.

       By using cardboard templates, I designed a secondary scatter shield which I later fabricated out of 3/16” hardened steel plate. The plate had some considerable weight but was necessary to insure driver/passenger safety. I mounted the plate on the GR-5’s frame rail which covers from the compressor to the power turbine. It will hopefully never be used...

       The next project to tackle was to make the seat for the Turbotug. I made a bench seat out of 5/8” plywood and then cut some furniture foam padding to fit the plywood cut outs. With a little help from my wife, I made fitted covers out of black canvas that I stapled to the plywood seats. I then used screws to hold the seat back to the frame and used hinges to mount the seat bottom. The seat bottom can hinge up to allow access to the propane tank below.

       The next system to tackle was the steering column and there was a lot to do. I had earlier set aside a 10:1 Alpha planetary gear box for this project so I dug it out of the rafters. The gear box was originally designed to be used with a servo motor to actuate industrial machines. I intended to use the gearbox to drive the steering linkage from the steering wheel. I had earlier purchased a go kart steering wheel, hub and shaft which I hoped would mate with the gearbox.  With a little luck the shaft fit the input collar perfectly so all I had to do was make a steering column.

       I removed the aluminum adaptor block from the gear box and made a 1/4” steel flange that I welded to an 1-1/2” EMT pipe. At the end of the pipe, I added a 5/8” ball bearing that will support the steering shaft. In a short while, I had the column complete and ready to mount to the frame.

       The steel adaptor plate on the other side of the gear box made for an easy way to mount it to the frame rail of the kart. I welded in the adaptor plate directly to the frame rail and then reinforced it with angle iron.

       I now needed to build a pitman arm to connect a tie rod to so I used a steel drive coupling hub and welded one up. Using what you have can sometimes be an art :0)

       To connect the gearbox tie rod to the wheels I had to make a “bell crank” so I welded a steel arm to the trailing steering arm assembly at just the right angle. I then connected up the system with a 3/4” x 24”  aluminum tie rod with 5/8” steel ball joints. The system worked flawlessly and I was even more enthused to finish this project.

       Although the steering system was hammered out, I could get nowhere without a gas and brake pedals. With a small pile of steel stock, I threw some pieces together and through trial and error, made up a pedal system.

       Because the floor pan is so low, I had to design the pedals with ground clearance in mind. I made a remote throttle arm that will allow me to set up a throttle cable to 3” of throw if needed.

       I needed to install a conduit to carry all of the control wiring to the control panel. For this I used 1” EMT and welded it to the frame which will protect the wires from damage below the floor pan. I then notched the floor pan and installed it with sheet metal screws.

       I wanted to add headlights to the Turbotug so I welded some mounting tabs to the knee guard and installed some fog lights that I got from my local auto parts store.

       To finish the headlight installation, I needed to cut out holes for the headlights in the sheet metal. This was a great opportunity for me to use my new plasma cutter. I had wanted one of these babies for a while and found a good deal on one. I don’t have a whole lot of experience with plasma cutting but it sure is neat. The unit I bought will cut up to 1/8” steel and does so effortlessly. There are a few talented fabricators that can cut out complex designs freehand in sheet metal that are amazing. Maybe I will have some time later to practice this art.

       My MIG welder is on the left and the plasma cutter is on the right. Once again, having the right tools is very cool indeed!!!

       All I had left to fabricate on the GRV-1 was the control panel plate and support bracket. By welding a 1/2” angle iron frame to the knee guard, I made a place for the control panel to bolt to. I then cut out some aircraft aluminum to fit the frame. I bolted the control panel plate to the frame and was finished.

       I will wait to see if there is anything I need to add to the frame before I paint it, otherwise the frame is complete. There is still more to be done but it will be focused on the GR-5 engine. The entire control system needs to be redesigned if I am going to add an “autostart” feature. There will also be some rearranging of the engine layout to add a spooling blower that will allow the engine to self start. I am sure that there will be some experimenting to be done to accomplish this. Anyway, wish me luck...

Until then, be safe!!!

Don Giandomenico


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