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1300W Yard / Garden Tractor

Plans Preview    Paid-For Plans

Page 1          Page 2

Detailed plans are now available for the Yard Tractor as part of our complete  paid-for plans sets or as an individual printed set.

 

Here's a quick video clip of my son "testing" the tractor - clip (2Mb) (Sorry I've lost the sound on this one. Yes - that's a 14ft steel framed trampoline hitching a ride at the end.)

 

I built a mini garden tractor a few years ago which worked great around the garden but looked a bit strange with its doubled-up mountain bike wheels. I decided to have another go but this time try and achieve a more conventional tractor look - conventional lawn tractor wheels and tyres are fairly easy to get and that has made a big difference. I have also fitted a bought tractor seat (right) rather than my usual home made upholstery which helps appearance, although I'm not sure yet if the mounting is correct visually!

 

Chassis - As with most of the vehicle designs on the site the tractor has a timber chassis and uses steel components locally where strength and toughness is needed - most notably for the drive transmission, axle, steering and braking components. 

 

 

Rear view on DIY yard tractor - unpaintedWheels - The tractor wheels are conventional turf tyre types - 16x6.50-8 at the front (from Northern Tool - see image below right) and 18x8.50-8 at the rear. The seating is positioned above the rear wheels to ensure good weight over the rear drive for traction. Four 12V 38AmpH or two 75AmpH rechargeable lead-acid batteries can be fitted and are housed low and forward of the rear axle in the tractor chassis and contribute to keeping the COG low and maintain a proportion of down-load over the front wheels to give adequate steering traction. There is enough battery capacity to give about two hours continuous running time between charges, but this depends on loading off course.

 

Drive - I've used a drive design very similar to that on the electric Voiturette, but this time geared down to give a slower top speed - about 6-7 mph so that much more of the motor power goes into drive torque at the tractor's rear wheels. Each wheel is driven by its own 24V 660W DC PM electric motor through a permanently engaged two stage roller chain transmission (approx 20:1 reduction).

Golf Cart and Tractor Replacement Tire Assembly — 16 x 650 x 8

Wheels from

NorthernTool.com (US)

 Northern Tool (UK)

Northern Industrial Tools Rigid Pan SeatWith this arrangement I should get rear wheel drive forces of about 55kgf (120 lbf) at the motors' rated torque/current output and up to two or three times this this for short duration pulls as the motors approach stall - plenty for hauling a small trailer about the garden and for operation on modest gradients. Higher drive forces than these will exceed the traction limits of the turf tyres and are not needed on this small machine. The effect of higher drive torques on the DIY transmission stresses would also need to be watched for higher power motors.

1300W DIY Electric Yard TractorThe single DC controller / double motor drive produces very effective differential behaviour on the rear drive wheels and the tractor has no problem turning at its full steering lock. The inboard wheel drive torque does rise during turning as it slows from its natural speed however this is not sufficient to affect the steering under most driving conditions. In the unlikely event that differential speed control is needed on the rear wheels to aid tight turning the simplest and most cost-effective way to achieve this is on this small machine is to operate the rear disc brakes independently to hold back the drive to the inboard rear wheel.

 

 

Continue to Page 2 .......

Detailed plans are now available for the Yard Tractor as part of the full download or CDROM sets - see the Plans Page here.

FREE preview versions of the assembly drawings for the yard tractor are available here. These do not include all the detailed part size drawings but may give interested readers a feel for the design and of the construction methods used. The complete plan set is available from the Plans page

(Note that some small lathe work will be required to complete this project.)

 

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