Innovation Put an End to the Hand-Crank Era

Claimed to be the “greatest single invention ever devised for tractors,” the Christensen self-starter made a possibly dangerous task safer and simpler.

| May 2019

Ford tractor demonstration between 1921 and 1922. Photo courtesy of the Library of Congress.

Anyone who collects antique tractors has spent time hand-cranking a recalcitrant engine. Some have even experienced the dreaded scenario where an ill-timed engine will “kick back,” causing a broken arm (or worse).

Even though inventors tried to develop mechanical self-starters using springs, compressed air and other ideas, until 1912 most all cars, trucks and tractors were crank-started. Not only were many folks injured, but it was widely believed that hand-starting prevented the “delicate” fair sex from driving.

In April 1908, Byron J. Carter, founder of the Cartercar and a friend of old, white-bearded Henry Leland, the boss of Cadillac, died of pneumonia. It’s been widely reported in the automotive press ever since that Carter’s illness was triggered by a chivalrous deed.

The story goes that on a snowy day a month or so prior to his death, Carter came across a woman driving a Cadillac that had stalled and he stopped to help. While he was cranking the car, it kicked back. The crank caught Carter in the jaw, breaking it. He never recovered, developing the pneumonia from which he died. His death from a crank-start kickback, especially on a Cadillac car, supposedly goaded his friend, Leland, to do something to solve the problem.

Couldn’t work – but it did

While that story may or may not be true, Leland was concerned about engine kickbacks injuring people. He contacted Charles Kettering to develop an electric starting motor and equip a Cadillac with the device. In that era, electric motor and storage battery technology was still sketchy. Experts from Westinghouse, General Electric and the German firm of Siemens & Halske all said the idea wouldn’t work.

It did, however, and by 1919, most passenger cars were equipped with an electric starter, many made by Kettering’s Dayton Electric Laboratories Co., better known as Delco. Now milady could merely press a button with her daintily slippered foot and her engine roared to life.

However, the fragile storage batteries of the day wouldn’t stand up to the pounding of a farm tractor on steel wheels bouncing over a ploughed field, or a heavy truck with solid rubber tires and heavy springs on the rough and rutted roads of that era.

ractor and truck owners still had to twist the crankshaft or flywheel of their big engines by hand with a crank or hand lever. Hand-cranking was not only hard work, especially in cold weather, but there was the ever-present danger of a broken arm from the engine kicking back.

Some tractor manufacturers furnished cold weather starting instructions for their tractor buyers, such as the following: “Important – Starting Motor in Cold Weather. Use small gasoline torch to heat inlet manifold and carburetor; remove spark plugs and warm them; prime cylinders and no trouble should be had in starting motor.” I wonder how many destroyed tractors and barns resulted from using a blowtorch on a carburetor with just one tiny leak.

Self-starter transforms the tractor

In 1919, Christensen Engineering Co. of Milwaukee introduced a self-starter that they claimed was “the greatest single invention ever devised for tractors.” The starter package (which cost $200) consisted of an air compressor, with a clutch to engage it with the engine, air tank, gauge and a control valve at the driver’s seat. There was a carburetor to add fuel to the compressed air, as well as an automatic distributor to shoot the fuel-air mixture into each cylinder in the proper firing order. Weighing only 40 to 60 pounds, the device could stand travel over rough terrain and hard use without getting out of order.

Widely tested here and abroad

And ad for the 1919 Lauson 15-25 tractor equipped with the Christensen starting system.

Christensen starters were tested by the makers of Lauson, Craig, Gile, Bates, Wallis and Illinois tractors, as well as several big city fire departments for use on fire trucks. It was claimed that fire departments in New York, Chicago, Detroit and other large cities adopted the system for their fire apparatus. The U.S. Signal Corps and Navy, the British Air Service, and the French Artillery Air Section also tried the starter on airplane engines. How many ever actually went into service is unknown, although John Lauson Co. did make the Christensen starter regular equipment on 1919 Lauson tractors.

A Lauson tractor ad in the Feb. 8, 1919, issue of Implement & Tractor Trade Journal points out that their 15-25 tractor featured the “Christensen Carburetion System” starter.

I don’t remember ever seeing a Christensen starter on a tractor at any show I’ve been to. From a collector’s standpoint, it would make a neat exhibit to have an old Lauson tractor equipped with one of these devices. FC

Sam Moore grew up on a farm in western Pennsylvania. He now lives in Salem, Ohio, and collects antique tractors, implements and related items. Contact Sam by email at

How did the christensen self-starter work?

The cover of a circa-1919 Christensen information booklet bearing the firm's slogan, "Makes a plaything of the biggest motor."

Starting a tractor motor, with the Christensen Starter, is easy, even on the coldest mornings. Just set the ignition switch, press the starter control valve button. Air is thereby admitted into the starter carburetor. There it is properly mixed with gasoline and distributed to the cylinders in firing order.

Warming a tractor carburetor with a blowtorch: not a good practice.

The motive power is air and is contained in a pneumatic compression chamber at a pressure of 250 psi. From this compression chamber, the air passes through a piece of tubing to the control valve, and thence through the Christensen unit’s simple, non-adjustable carburetor, where it becomes saturated with gasoline, kerosene, or whatever fuel is used, thus being transformed into a highly explosive charge.

The air tank, compressor and injectors of the Christensen system

Then this explosive charge, already under compression, is forced by the air pressure behind it into a correctly timed distributor.

The explosive charge thus passes into each cylinder, through a check valve, and is delivered under pressure to each cylinder at the beginning of its power stroke. This explosive charge not only forces down the piston by reason of being under pressure, but at the same time is exploded by the spark plug, thus starting the engine.

As soon as proper firing has been taken up by the regular ignition system you release pressure on the starter button. The process is even simpler in action than in description.

– from a 1919 booklet produced by Christensen Engineering


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