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1300W Yard / Garden Tractor - Page 2

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Steering - The front wheels of the Yard / Garden Tractor have a tilted king pin steering geometry with Ackerman type linkages and are operated by the steering wheel via a geared steering lever to lighten the effort required to turn the front wheels. This steering geometry seems to have reasonable self-straightening characteristics and tends to return to center when the steering wheel is released. The front beam axle is pivoted to help keep all four wheels of the tractor in ground contact when operating on uneven surfaces - there is no other suspension other than a compression spring I tried to build into the seat support which I removed in the end in favour of a more rigid support.

 

 

Electrical - A 150 Amp 24V motor speed controller is housed under the tractor's ventilated front cover. The single 24V controller is fully rated for drawing currents at 24V and is used to drive both drive motors which are wired in parallel. DIY Yard Tractor BuildHigher voltage systems could be considered, however a 36V system would require either 3 or 6 x 12V batteries and would lead to problems fitting them in the space available and a 48V system will lead to additional un-needed expense in the motor and controller selection. 24V DC provides an effective and inexpensive drive on small EVs - a more cost-effective solution than an AC drive on this size of tractor.

The controller gives the tractor its variable speed forward and reverse drive and dynamic braking capability. My experience of these electrical drives is that they give very smooth speed control even when the vehicle is quite heavily loaded and it makes for a smooth running, controllable tractor. Mechanically independent braking is from two disc brakes incorporated into the drive transmission although the dynamic braking from the drive motors and 4-quadrant speed controller is effective in slowing the tractor when the power is removed or reversed. As mentioned above  it would be possible to use separate brake pedals for each rear wheel disc brake to aid tight turning - as is the practise on larger tractors, at the moment there is a single heel operated brake pedal for both wheels. I'm not sure about the parking brake design yet but this will probably be a lever operating the foot pedal.

DIY yard tractorI've tried to build in plenty of turning room at the front wheel arches for the wheels and the tractor's turning circle is therefore tight for good manoeuvring in the yard and garden. The position of the tow bar allows quite acute angles between the tractor and towed trailer.

I've gone for a British Racing Green painted finish with matt black on the chassis and sub structures  - the green looked quite good in the rendered CAD images but red might also be an attractive option.

 

 

The CAD rendered image on the left shows the tractor with chassis and bonnet (hood) structure removed so that you can see the arrangement of controller, batteries and rear wheel drive.

 

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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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