Re: More Narrow Gauge Garratt Questions

Beyer-Peacock always stated that one of the advantages of the Garratt design was the ability to run at high speed. The boiler didn't have to be mounted above the running gear, so a low center of gravity could be maintained. In addition, the boiler unit describes a chord across curves,reducing the overturning moment. They are described as running very smoothly at speed, even on straight track, due to the boiler pivot not being at the center, but near the rear of the engine bogie. This permitted the entire wheel base to aid in stability.

The reduction in weight due to fuel and water use was claimed to be uniform across both engine units and that performance didn't suffer as a result. Certainly the factor of adhesion would be reduced, but apparently the design was not particularly slippery even when light.

The 42" gauge GMAM class 4-8-2+2-8-4 Garratts had such small forward water tanks that they pulled water bottles as a matter of course, and the front tank was generally left full. I've heard accounts that in later years, when a front tank leaked, it was sometimes filled with coal to keep the front unit factor of adhesion at acceptable levels.

Michael Allen