Basic gearbox design for an endurance record

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Joined: Wed Aug 17, 2016 1:49 pm

Basic gearbox design for an endurance record



I really enjoy some of the discussions on here and was hoping I could get some guidance on my own project. The goal of this post is to help me understand the space requirements so I can start to layout the chassis. I'd also like to gain a better understanding of the scope of what's required so I can approach some of the prototype gearbox manufacturers and not come across as a complete idiot. (To be fair I have spoken to emco and weiseman in the past and they have been very nice in the past on other projects).

A little about myself for context. I am an aerospace technician with some engineering(Purdue) education. I have been lucky to work on and build some pretty awesome race cars previously. Now I get to wind composite parts that are on launchers and in orbit. I occasionally track a D Sports Racer when I have the time. Also started to build a tt-10 turbine powered enduro kart a few years back but shelved it for a multitude of reasons but might finish it and run it for a shorter distance on salt to figuru out what's involved with operating a vehicle on salt for long distances.

The goal is to build a turbine vehicle to set new FIA endurance records up to 100,000 miles. Here are some engine specs.

Maximum output is 24,000rpm and minimum usable is around 14,500rpm. Peak torque is around 700 lbs/ft at 1,000rpm and tapers off to 375 lbs/ft at 24,000rpm.

The vehicle will need an axle output of around 3,400-3,900rpm to run at the speed I'm targeting.

To hit 100k miles this vehicle will need to transmit roughly 1250hp through the drive train for at least 400hrs plus 100hrs for testing.

The other big caveat is the ability to operate at lower speeds as well requiring multiple ratios(40:1, 24:1, 14:1, and 6.5:1 seem to accomplish what I have in mind). The other big one is needing all 4 wheels driven due to limited traction.

What kind of ring/pinion ratios should I plan for? How large should the ring gear be? What type of gearbox architecture would be recomended? I am open to other power transmission technologies as well.

I appreciate any and all feedback. Also realize I am only looking for general sizes/loads since I'm am in the very beginning stages of designing this vehicle.


Joined: Thu Jun 16, 2016 5:44 pm

Re: Basic gearbox design for an endurance record


Your pinion/gear sizes will depend on a multitude of variables. But for concept design I think you should start by calculating the contact and bending stresses that the gears will experience. From there you can iterate and play around with your gear module/number of teeth/material type/ face width to get an idea of what will withstand the forces. I'm currently in the design phase of a gearbox for a plasticising screw assembly and the calculations can get quite involved so if I was you I'd get some literature on the subject. It will also help massively to code all the calculations (I used MATLAB) in order to speed up the iterative stuff.