Sort of O/T: wagon wheels...

Okay, so my son was watching a rerun of Little House on the Prairie. He noticed freight wagons hauling sacks of grain had larger rear wheels than front wheels. Then he realized that tractors are like this, too. He asked me why. For tractors, I am sure that it is for traction, but horse drawn wagons? Can someone help me answer this question and perhaps salvage some of my reputation?

Thanks for your help.

Christopher

Probably because of the turning radius, wouldn't turn very sharp if front wheels hit wagon.

The front wheels where smaller because with the solid front axle the wheels had to go in under the wagon box to steer. The larger rear wheels could carry more weight and where placed closer to the center of the wagon so they took a greater share of the total load.

The front wheels are smaller so they can turn tighter before they gouge the lower corner of the freight box. The larger diameter wheels pulled more easily over the rough roads, and typically the wagon was loaded heavier on the rear wheels to make the steering easier for the horses. Some wagons have a cast metal guard to prevent the turned front wheels from gouging a hole in the box lower corner.

I hope the little guy is satisfied with this answer.

Paul in MN

Tractors and small fron tires.
From the first steam powered traction engines to today's smaller tractors, the engines powered the rear wheels. There are many 4 wheel and multi wheel big and small wheel design exceptions to this idea, but they are no more.
The fronts were small for cost reasons as well as turning considerations. When Powerful 100+ hp machines were introduced, manufacturers of machine components fabricated drive systems to add Front wheel assist.
When really big articulated tractors appeared the wheel sizes were equalized.
THere are always exceptions to the rule, but this is a generalized answer. Jim

Historically wooden horse drawn wagon gears had smaller front wheels to enable the front wheels to ,in a sharp turn ,left or right,avoid rubbing against the wagon box/bed. Early in the last century on some light wooden wagons gears ,mostly in european countrys the front and rear wheels are the same dimension. In the new world when wagon gear builders adopted steel wheels for thier running gears front and rear were the same size.Why were the rear wheels of say a Conestoga wagon gear larger than the fronts? Good question,I don"t know the answer to that although I think there must be a logical answer. Suppose that if a wagon with a load got stuck on a road of mud in that era that the front was sort of pulled upwards and forward from the tractive effort of the heavy horse or horses pulling it while the large rear wheel was a good place for men on both sides to apply weight and muscle to get the wagon moving. a small wheel on the rear would be hard for a person to grasp ahold of to help extricate the wagon from the muc.

Historically wooden horse drawn wagon gears had smaller front wheels to enable the front wheels to ,in a sharp turn ,left or right,avoid rubbing against the wagon box/bed. These wagons would have a solid axle and a fifth wheel system on the front which allowed the wheels to be steered.No automotive type steering in that era.Early in the last century on some light wooden wagons gears ,mostly in european countrys the front and rear wheels are the same dimension. In the new world when wagon gear builders adopted steel wheels for thier running gears front and rear were the same size.Why were the rear wheels of say a Conestoga wagon gear larger than the fronts? Good question,I don"t know the answer to that although I think there must be a logical answer. Suppose that if a wagon with a load got stuck on a road of mud in that era that the front was sort of pulled upwards and forward from the tractive effort of the heavy horse or horses pulling it while the large rear wheel was a good place for men on both sides to apply weight and muscle to get the wagon moving. A small wheel on the rear would be hard for a person to grasp ahold of to help extricate the wagon from the muc.