Inspiration, Transmission

Once I’d settled on building a mini Landrover Defender style car, I wanted it to be a true 4×4 rather than the rear wheel drive only that most tot rods / kids ride on cars are.

There are many ways of achieving this. One of the first choices to be made is how to get power to the wheels.

This has been done in different ways by different manufacturers.

As my design is destined to be electrically powered it opens up the possibilty of having multiple motors to provide the power to the wheels.

Multiple motors have the advantage of reduced transmission requirements / joints / drive shafts. The down side is the supporting of the in wheel motor arrangement with a steering mechanism at the front end and if some of the wheels loose traction then all the load is put through a much smaller capacity transmission.

 

Single power plant has the advantage of being able to use much more widely available motors/controllers and has the advantage of being more easily upgraded at a later date. This leaves how to get the power from the motor to the wheels.

Traditional four wheel drive systems use shafts to transmit power to front and back

This example was constructed by a very skilled gentleman, you can view his construction log here Toylander 4×4 MB43 build

 

As can be seen above, shaft drive often relies on multiple articulating joints to allow shaft to flex. Here are a variety of methods of connecting two shafts that need to transmit torque through an angle.

Traditional Universal joint available from many industrial suppliers

Drive shafts from the world of Radio controlled cars showing a mix of universal joints and ‘dogbone’ type drive shafts which allow variations in distance between joints

Constant velocity joint used in the front wheels of pretty much all front wheel drive cars in modern times.

exploded view of a CV joint

animation of CV joint showing operation under extreme angle

Plunge type CV joint allows a change in distance between joints but at the cost of reduced articulation angle

Rubber donut joint allows medium articulation, minor distance compensation and vibration dampeming, however has limited life.

Flex disks are similar to the donuts but tend to have lower articulation angles

Dog bone drive shaft from a Fiat 600, showing has they can be upscaled beyond lightweight duty of the radio controlled worl applications

Impact driver swivel joints that act like the dog bones in RC car driveshafts

A variation on on the pin and slot impact swivel joints, this works more like a CV joint without all the extra balls and bits

Another variation in the impact swivel joints, this time using what looks like a captive ball ended allen key to transmit the torque

A ball ended torx key would provide a similar plunge type CV joint action if one could be found that’s large enough to take the torque

Ball ended allen keys are certainly available large enough to transmit sufficient torque

Allen key or hex style drive shafts have been used before in the RC world, these half shafts are from a 1980’s buggy made by Tamiya, The Frog. Though later revisions of this car used the more sandard dog bone design.

A more recent advocate of the hex ball design of a plunge joint is the Henes Broon T870 ride on 4×4

 

Shaft Drive is not the only way to get power to the front and back of a vehicle.

RC cars have been using belts in four wheel drive applications for years.

 

And this rather unique racing car from DPcars uses chain drive to distribute power from the engine to the front and rear of the car.

MINOLTA DIGITAL CAMERA

MINOLTA DIGITAL CAMERA

MINOLTA DIGITAL CAMERA

 

Another key component in a transmission is a Differential here’s a bit of my inspriation on the subject: Inspiration, Differentials

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