How Well Do You Know Tractor Transmissions?

We want to share important information that will give you excellent insights into the various tractor transmission types and their history.

And as a quick aside --- we are here to help you purchase a new tractor, parts, and implements when the time is right.

Let’s dive into the details.

Introduction

Most older farm tractors use a manual transmission with several gear ratios --- typically three to six --- sometimes multiplied into two or three ranges.

This arrangement provides a set of discrete ratios that combined with the varying of the throttle, allows final-drive speeds from less than one up to about 25 miles per hour (40 km/h).

Operating Speeds

The lower speeds are used for working the land and the highest speeds are used on the road.

Slow, controllable speeds are necessary for most of the operations performed with a tractor.

They help give the operator a degree of control in certain situations --- such as field work. When traveling on public roads, the slow operating speeds can cause problems, such as long queues or tailbacks. These can delay or annoy motorists in cars and trucks. These motorists are responsible for being duly careful around farm tractors and sharing the road with them, but many shirk this responsibility. So various ways to minimize the interaction or minimize the speed differential are employed where feasible.

Some countries (for example the Netherlands) employ a road sign on some roads that means "no farm tractors." Some modern tractors, such as the JCB Fastrac, are now capable of much higher road speeds of around 50 mph (80 km/h).

Designs

Older tractors usually have unsynchronized transmission designs.

They often require the operator to stop the tractor to shift between gears. This mode of use is inherently unsuited to some of the work tractors do today. Luckily, it has been circumvented in various ways over the years.

Shifting

For existing unsynchronized tractors, the methods of circumvention are double clutching or power-shifting --- as both require the operator to rely on their skill to speed-match the gears while shifting.

They are undesirable from a risk-mitigation standpoint because of what can go wrong if the operator makes a mistake. Transmission damage is possible. Loss of vehicle control can occur if the tractor is towing a heavy load either uphill or downhill.