The Brennan Gyro-Monorail.

Updated: 20 June 2004

Having found a gyroscopic monowheel, the Museum of RetroTech now (15 Oct 2001) proudly presents... a gyroscopic monorail vehicle. Here is a truly wonderful piece of work.

The Brennan Gyro-Monorail was 40 feet long and weighed 22 tons, and was designed to carry 10 tons. Speed on the level was 22 mph. The vehicle was balanced by two vertical gyroscopes mounted side by side, and spinning in opposite directions at 3000 rpm. Each gyroscope was 3.5 feet in diameter and weighed 3/4 of a ton each. They were enclosed in evacuated casings to reduce air-friction losses. The rotational axes were horizontal.

In the Gillingham tests the vehicle was fitted with two petrol engines. A small 20 hp unit powered the gyroscopes, drove an air-compressor (for braking?) lighted the car, and propelled it at slow speeds. A larger 80 hp engine was used for high-speed propulsion.
Brennan patented the concept in 1903.

Left: The Louis Brennan gyroscopic monorail, demonstrated to the press at Gillingham. Kent, on 10th November, 1909. Note the soldiers standing on the rear platform- apparently 40 of them. The sleepers of the test track were 3.5 ft in length, laid 2.5 feet apart without ballast. The steepest gradient on the track was 1 in 13, and the sharpest curve had a radius of only 35 feet. Note double-flanged wheels.

Left: This looks like a test-track to prove you could back it in a wye and so turn it round. If this machine was intended to pull wagons or coaches in the usual way, then there appears to be a problem. Surely each vehicle in the train would need its own gyro-balancing system, complete with power supply? Furthermore, it only take the momentary failure of one gyro system to cause the mother of all derailments. Not a war-winning weapon, I feel, and I imagine the War Office thought the same thing.

Above: Two pictures of a trial run with the machine loaded with civilian passengers.

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THE BRENNAN MODEL GYRO-MONORAIL
The principle was first demonstrated by a model shown to the Royal Society in 1907. The electrically-powered model travelled along a single wire 6 feet above the ground, using grooved wheels, and maintained its balance despite its forward motion being repeatedly stopped, and the wire violently swung. On the strength of this, Brennan was granted a subsidy by the War Office to build the full-scale machine.

Left: The Brennan model in action, using just one of a pair of rails. The model was 5 ft long and 18 in wide, with a total weight of about 175 pounds. The accumulators to power the electric motors can be seen at the back of the load-deck.

Left: The Brennan model, with a cutaway showing the location of the two gyroscopes. The cylindical structures just above the wheels at each end are presumably the electric motors for propulsion.

Left: How the two gyroscopes were mechanically coupled to utilise the precession forces. When the car tilted, each gyroscope would try to precess by rotating round a vertical axis. This would not in itself stop tilting, as the torque is in the direction of steering rather than tilting. However, two gyros spinning in opposite directions produce precession forces in opposite directions, and when these are geared together as shown the result is a reaction on the horizontal shaft that counteracts the original tilt. I hope I've got that right.

Bibiliography:
"A full description of the mechanism, with a mathematical discussion on the subject, is given by Mr. H. Cousins in the issue of Engineering for Nov. 21st, 1913, and following numbers."

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