Design Tips & Plans

Need ideas or stuck for what to do? Google probably provides the best source of info and images for inspiration.

However trolleys have many different names - in the USA Soap box derby racing, in Australia Billy Cart racing, in NZ we've kind of adopted everything, Trolley derby is probably the favourite in NZ however Soapbox, trollley billy cart go kart, gravity racers are all recognised names - Click Here to check out a Google Images page for Trolley building ideas.

If you want to build a good tried and tested Trolley that was specially design for the Nelson Trolley Club, check out the Formula NZ Trolley Design below for full design plans in PDF format. These trolleys make a great first time trolley that are very competitive and relatively easy to build and drive and can be modified over several years as the driver grows in confidence.

 

 

TOP TIPS FOR SPEED, SAFETY & ENJOYMENT:

 

We strongly recommend the use of Pneumatic tyres, that is inflatable tyres, with decent bearings on your wheels. Aim for at least a 8 inch wheel - something off a childs BMX, Mountain Buggy or baby stroller. You can run solid rubber tyres however the roughness of the road surface doesn't make for a good ride. Small wheels can often be unstable at high speed and harder to control.

The axle track and wheel base of your trolley can also majorly effect stability and control at high speed.  If a trolley has a long wheelbase and narrow track it is usually very stable but slow to change direction. A short wheelbase and wide track, meanwhile will change direction easily but sometimes too quickly and even when you don't want it to.

 

"Formula NZ Trolley"

Your axle "track" is essentially the width from one wheel to the other. Your wheel base is the distance between your front and rear axles. Generally speaking the wider your "track" the more stable your trolley and the easier it is to steer. If your track is too narrow and wheel base is short the trolley can flip easily and steering is too jerky. However keep in mind that wider trolleys often have more frontal area so worse aerodynamics and more drag = slower speeds. In widening your track, try and keep the main body of your trolley narrow for optimum aerodynamics.

 

 

"The Golden Ratio"

More traditionally applied to mathematics, geometry, art, and architecture, the Golden ratio may be applicable to your trolley track vs wheelbase. Many race cars and go karts come close to using the golden ratio for their design of 1.618:1

 

Example 1) if your wheel base is 1618mm then your wheel track should be 1000mm.

 

Example 2) if your wheel track is 600mm then your wheel base should be 1.618 X 600mm = 970mm.

 

Example 3) If your wheel base is 1000mm then your wheel track should be 1000/1.618 = 618mm

 

Essentially two quantities are in the golden ratio if their ratio is the same as the ratio of their sum to the larger of the two quantities.

 

 

Center of Gravity

The height of your trolley and it's center of gravity can also majorly effect your stability. If you have a high "sitting on top" drivers setup this will increase your centre of gravity and you will require a wider track otherwise you can flip your trolley. The lower your centre of gravity, eg the lower the seated driver, the more stable your trolley will be. 

The traditional kiwi trolley often runs on motormower wheels or small trolley wheels, however these won't give you enough speed. Remember generally the bigger the wheel the faster you'll end up going.

Our design guide has been put together to help you design everything from the most basic trolley up to a real speedster so you get out there and play with gravity.

Trolleys can be as simple as the old soapbox with 4 pram wheels (but please no rope steering) or a purpose-designed, 3 wheeler recumbent with an aerodynamic carbon fiber body! 3 Wheelers have less friction and drag so generally go the fastest - though may not be as stable as 4 wheelers.

If you are designing and building your trolley to participate in the derby, then you need to ensure that your trolley design complies with the Rules for Race Day

 

A really great book full of plans and trolley designs that can be found in most libraries including Mangere Bridge Library is "The Billy Cart and Trolley Bible", by Glyn and Jane Bridgewater. It can also be purchased online through Fishpond.co.nz

• For Basic Trolley Design Ideas check out Brian Fangio Smiths suggestions

• Some Basic trolley and kart plans can be found here - kartbuilding.net

• If you're really keen why not try building a trolley size 1932 Ford Sedan - check out the Instructables.com website

• For traditional All American Soapbox Derby carts and plans check out the official website for plans (pretty complex but great tips on steering and brakes in these plans) - AASBD.org

 

 

Fundamentals

If speed is your goal, the action of your wheels and their rolling resistance is the most important aspect to consider.

Once you hit 40km/h, aerodynamics also impacts on your maximum possible speed.

Of course, speed is useless if you haven't got control, so pay careful attention to your steering, brakes and structural rigidity.

Keep your construction light!! Contrary to popular belief, weight is an enemy to every trolley. We have a 45kg weight limit which you cannot exceed (for safety of spectators in case of loss of control, and drivers in case of a roll over)

Shaping techniques for the body of your trolley are almost infinite, ranging from cardboard and sticky tape to carbon fibre.  Whatever you use can make the most basic trolley look like a speed demon.

 

 

Wheels:

The lighter a wheel is the more acceleration it will have but a wheel must also be strong enough to withstand the forces of steering and braking.

The smaller the area of contact the wheel has with the road the less drag the road exerts on the wheel. This is great for acceleration but dire for braking - you see, it is all compromise.

Wheel bearings play a critical part in the speed of a trolley. Make sure your bearings are clean and use light oil.

 

Your choice of wheels determines your rolling resistance. This is the amount of resistance your wheels have to the unavoidable pull of gravity that is trying to make your trolley career down the hill.

The perfect trolley wheel is a compromise between weight, strength, contact area, braking performance, rolling efficiency and cost.

Old wheelchair wheels are ideal as they have very strong axles and bearings. They can be attached directly to the side of the trolley. These can sometimes be found at Refuse or Recycle Centres or also check out auction sites on the internet to see what is available.

Old 10-speed bike wheels make great, cheap trolley wheels providing they are pumped up hard. However this type of wheel must be supported on both sides of the axle.

 

Old motor mower wheels are fine but don't usually have bearings. 

Pneumatic (air-filled) and solid trolley wheels with bearings can be bought for about $40 a pair from Bunnings or Mitre 10 Mega.

 

 

Using Bike Wheels: 

Most bike wheels use a 3/8 inch axle however there are some that use a 1/2 inch axle which tend to be much stronger. If using bike wheels it is recommend to have some sort of support on the outside of them to stop them "tucking in" when cornering or under speed.

Spoke strength also effects the strength of the wheel - BMX wheels are designed for a bit more punishment so tend to have stronger spokes/more spokes, and stronger rims. The larger the wheel the more likely it is to buckle if your trolley is very heavy and/or your spokes or axles are weak. The course may be reasonably straight however in the case of an unforeseen accident you may be required to take "evasive action" and the axles and spokes may not handle the jandle when asked to turn.

 

 

Wheel Chair Wheels: 

If you can want the full monty and can find some wheel chair wheels these are very good as they have a very strong axle that is self supporting, they normally have very good bearings, and strong spokes. These are generally quite large so aren't always the best for acceleration however may give you a higher top speed (not probably relevant on shorter courses like ours.)

 

 

Brakes:

"Brakes are probably the most technically challenging aspect of building a trolley."

Sam Laidlaw: designer of five Nelson Monarch of the Hill-winning trolleys

 

There are two common braking systems:

Deadman Braking  - this is where the brakes are held in the 'brakes on' position by a spring, bungee or bike inner tube.  To race, the driver pushes the brake lever and the wheels are released.  This is a great system for young drivers as the brakes only stay off while the driver is in control ~ the instant they freak out and move their feet, the trolley slows down.

 

Active Braking  - Cars & bikes use an active braking system.

There are many ways to create rudimentary versions, for example:

• A large piece of car tyre rubber on a lever activated by the drivers foot;

• A hinged lever carrying the foot pressure via a rod to the back wheels.

 

If you use 10-speed or wheelchair wheels, it will be possible to have brakes on all wheels.

 

If you have a fixed rear axle you can incorporate a bike disc brake.

 

 

Shaping:

There are essentially two types of vehicle construction:

Chassis and Body

Monocoque

 

A chassis and body structure has all strength in the chassis and the skin or body is cosmetic.

In a monocoque design the chassis and body elements are combined to create a more rigid and lighter vehicle.  Airplanes are an example of extremely efficient monocoque design.

 

Both systems work well for trolley building as long as the weight and type of material is used not only to maximize performance but also to ensure the safety of the occupant, other drivers and spectators.

 

For a monocoque design, 3mm - 5mm plywood makes a great overall skin structure, which can then be filled out with polystyrene, cardboard and brown paper.

 

A design that uses chassis and body construction can really take advantage of lightweight skinning materials.

With the rigid structure taking the weight of the driver and the stresses of the braking and steering systems you can use polystyrene, cardboard, sticky tape, PVA glue and paint to create an elaborate and aerodynamic skin.

 

Make sure you provide clear lifting points for loading on and off the trucks!!

Ensure any sharp or solid protrusions inside or out are well padded for yours and others safety.

For stability and reduced air drag, position as much of your weight below the axle as possible.

And remember, a light trolley is a fast trolley!

Good Luck!

´╗┐

(This information has been collated by Andy Williams´╗┐)

 

Designed for use by the Nelson Trolley Club these make a competitive trolley for children up to around 10 years old with a minimum of materials required.

 

A safe and easy to build, cheap, entry level trolley for kids from 2 to 10 years of age. 

This is a "ONE design" trolley built almost entirely from a single sheet of 12 mm construction plywood. These run best with 6 to 8inch wheels - Mountain buggy or similar stroller wheels are one of the best options.

 

This will be a great project for you and your child and will get them interested in the Derby and some basic construction techniques.

 

You can Download the Formula NZ Plans in PDF Format here

 

To view and download a full copy of the design drawings with measurements  CLICK HERE

Designed for use by the Nelson Trolley Club these make a competitive trolley for children up to around 10 years old with a minimum of materials required.

 

A safe and easy to build, cheap, entry level trolley for kids from 2 to 10 years of age. 

This is a "ONE design" trolley built almost entirely from a single sheet of 12 mm construction plywood. These run best with 6 to 8inch wheels - Mountain buggy or similar stroller wheels are one of the best options.

 

This will be a great project for you and your child and will get them interested in the Derby and some basic construction techniques.

 

You can Download the Formula NZ Design Plans and Instructions in PDF Format here

 

To view and download a full copy of the design drawings with measurements  CLICK HERE

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