Pp wheeled vehicles powered by animals

WHEELED VEHICLES

POWERED BY

ANIMALS

They come in many sizes and shapes,

BUT SOME FEATURES ARE IMPORTANT

NUMBER OF WHEELS

NUMBER OF SHAFTS

2 wheels/1 axle (i.e. cart)

1 shaft(disselboom)

4 wheels/2 axles(i.e. wagon)

2 shafts

Even though they occur in combination, each has its own effect on vehicle as

well as animals.

2 WHEELS (i.e. less expensive to

construct)EFFECT ON VEHICLE EFFECT ON ANIMAL/s

Better suited to lighter loads

May not need more than one animal

Load almost impossible to balance over axle

Most of load weightgoes forward onto animal.If backward, shaft/s lifted from horizontal.

4 WHEELS (i.e. more expensive to


Larger & heavier load possible

Greater pulling and braking force needed on slopes

Load better balanced over axles

On level ground, only resistance of wheels important

1 SHAFT (disselboom) (i.e. less expensive to


More strain required for turning

Required in pairs suited to each other

Any forward weight goes to one place (end of shaft)

Weights and forces need to be distributedevenly over both animals, especially those nearest to vehicle

2 shafts (i.e. more expensive to


Shafts share turning strain

One animal takes all weight and exerts all braking force

IMPORTANT COMBINATIONS(being those most commonly used)

2 SHAFTS + 4 WHEELS

Most expensive

1 SHAFT + 4 WHEELS

2 SHAFTS + 2 WHEELS 1 SHAFT + 2 WHEELS

Cheapest

Drawings of vehicles taken or adapted from ICSID ( ) 2005. Animal-drawn carts. Report to Interdesign meeting on Sustainable Rural Transport, Rustenburg, South Africa, April 2005. Pretoria, South Africa: South African Bureau of Standards. NOTE THAT this refers to wagons as ‘high capacity carts’.

2 SHAFTS + 4 WHEELS ADVANTAGES DISADVANTAGES

Shafts share turning strain (but vehicle doesn’t turn as easily)

One animal takes all weight and exerts all braking force


Greater pulling or braking force needed on slopes



For pulling, but not for taking weight or braking, extra animals can be added in tandem position.

1 SHAFT + 4 WHEELS ADVANTAGES DISADVANTAGES

Two animals can share weight and exert braking force

Greater pulling or braking force needed on slopes


Weights and forces need to be distributed evenly over both animals, especially those nearest to vehicle




2 SHAFTS + 2 WHEELS ADVANTAGES DISADVANTAGES

Shafts share turning strain (but vehicle doesn’t turn as easily)


Better suited to lighter loads(not necessarily an advantage)

Most of load weight goes forward onto animal.If backward, shaft/s lifted from horizontal.

May not need more than one animal (in fact rare to see more than one powering this type of vehicle)


ADVANTAGES DISADVANTAGES

Two animals can share weight and exert braking force


Better suited to lighter loads(not necessarily an advantage)

Most of load weight goes forward onto animals.If backward, shaft/s lifted from horizontal.

Animals required in pairs suited to each other

Weights and forces need to be distributed evenly over both animals, especially those nearest to vehicle

1 SHAFT + 2 WHEELS


From this it can be seen that the

WORST combination is

1 shaft + 2 wheels

When there are only two wheels, so that weight balance is a problem,

it is essential that no kind of girth/cinch is used under the body of the animal,

and no ‘collar’ type harness

It will also be noticed that the chief problems are:

• Vehicle turning

• Distributing weight/force to proper place on animal/s

VEHICLE TURNINGis easier when there is only one

shaft (disselboom), as long as it is centrally mounted.

With more than one animal, torque (for horizontal turning) should not be exercised through vehicle body, but

through a central pulling point.

THE DISTRIBUTION OF WEIGHT is also more difficult to solve when there is more than one animal, i.e.

when there is only one shaft (disselboom)

ALL WEIGHT IS BORNE BY THE ANIMALS DIRECTLY IN FRONT OF VEHICLE;

the animals in front of them only help with the pulling, and then only if hitched properly.

The shaft (disselboom) in fact acts as a lever, with the axle as fulcrum,

to transfer the weight to the END OF THE SHAFT

Each species of animal has different parts of the body for different

strengths. The donkey here is an example.

Note that horses and donkeys have different shapes

A ‘withers strap’ joining the animals to share the weight may work well enough

on horses

But gives many problems on donkeys

This is why a ‘withers strap’ for a horse, ends up as a ‘neckstrap’ on a donkey, where it can do a lot of

damage.

But there is a solution(which works not only for donkeys, but

for horses and oxen too)

ESSENTIAL FOR WHEELED VEHICLES:A breechstrap enables an animal to handle braking (forward force from

vehicle) as well as backing.

This uses traditional elements of harnessing and hitching, so nothing unfamiliar, and only eliminates the

withers strap/neckstrap

Simple technology, readily available in most rural areas.

In practice, the result is comfortable animals, easy in their work.

FACILITATION AND CONSULTANCY SERVICES

Peta A. Jones, MSc PhDPO Box 1695 MUSINA 0900 South Africa

cell +27 (0)83 686 7539 e-mail [email protected]

All the things your donkeys can do • Problems to be solved with donkeys • How to make equipment for donkeys • How to look after your donkeys • What your donkeys are worth •

How to earn money with your donkeys •

mailto:[email protected]

Pp wheeled vehicles powered by animals

Engineering

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