Thread: Caster wheel Design angle off vertical

Hello All,

Is there a specific angle off vertical between the horizontal pivot point and the offset of the wheel axle to be considered when designing a caster wheel arrangement? I would like to be able to use existing wheels and make my own caster arrangement for some specific purposes. I have been looking for a while and no commercially available unit seems to fit my requirements. It looks like I will have to custom make something. Knowing some design tips and tricks about casters would be much appreciated.

1. In the diagram the red line is the centre line for the main horizontal swivel point for the caster that passes vertically down
2. The yellow line is the vertical point passing through the wheel axle
3. The blue line represents the angle or rake which passes between the horizontal swivel point to the axle of the wheel
4. The brown lines represent the horizontal distance between the horizontal swivel point and the centre of the wheel axle
5. The top horizontal dimension line represents the distance between the centre point of the horizontal swivel point and the centre of the wheel's axle.

Do all these 5 factors go together to form an effective and efficient caster design?

Kind regards
Lionel

Hello John and RandLover

I have a heavy duty three point crane jib that is way too big for my little Yanmar four wheel drive tractor. I was going to use the three point linkage side of the jib to sit a trailer axle and wheels under. Then directly under where the long reach hydraulic ram goes - close to the jib frame's pointy end of the triangle, I was going to mount a similar arrangement to the front wheels of an old Farmall H tractor. See the photograph.

My sister's boyfriend is an aircraft frame mechanic - aviation engineer, during a visit here he ticked my project off as being both feasible and practical. His one comment was I should think of incorporating a caster angle into the copy of the Farmall H pivoting wheels. The whole unit will be mounted via a tow hitch to my tractor. This arrangement allows for the crane unit and its load to be self supporting as it is a towed unit. Not relying at all on the weight of the tractor to counterbalance the load. The wheels and tyres will be something from the wrecker with the donor as a Holden or Ford where the hubs are readily available from any trailer place or auto parts store.

I think the idea of the Farmall H style front wheels being arranged as a caster configuration is so it turns around by itself with changes of direction. Unlike the tractors the front wheels will not be controlled by a steering arrangement.

Instead of having the 'legs' of the caster wheel being external to the wheel - like the Farmall H there will be a central king pin column. Then a triangle shape made out of thick plate and a steel hollow section frame in the shape of a triangle to create a caster angle and mount the two wheel hubs and stub axles off. The Farmall H had a central "P-Wheel" bow shaped frame that went in between the wheels. Instead, I will be using hollow section steel and round bar instead to form the pivot and hub assembly. More like the older 1936 F12 Farmall tractor's front wheel arrangement.

The terrain traversed will be out in a flat grassed - okay weeded - paddock and towed either onto a concrete slab or a recycled bitumen road-base mix hard pad.

Farmall H tractor photographs accessed 11th August 2025 from, Farmall H - Wikipedia
Farmall H parts diagram accessed 11th August 2025 from, 302 Found
1936 International F12 Farmall tractor accessed 11th August 2025 from, https://www.gumtree.com.au/web/listi...les/1335732577


Yes, it is a lot of work and there are no doubt better options available. I would like to do it just for the challenge and the fun. Get the jib out from just leaning idle against the wall in my shed and have it out doing some work. I was going to buy the front wheel arrangement off a spares tractor - until the bloke told me how much money they wanted for the parts. It went a long the lines of extortionate and 'stand and deliver'. I walked away instead.

Kind regards
Lionel