The steam waggon continued to do sterling work long after the internal-combustion engine had usurped steam in the motor car. Of these, the Sentinel was one of the most successful British makes. This Snapshot of their 6-ton waggons loaded with raw cotton dates from 1923, and is one of several pictures of these steam workhorses found in the promotional booklet produced by Trafford Park Estates in Manchester (from where Snapshot 156 also came). All of them are in the livery of the Port of Manchester Road Service Ltd. According to an article in the 20th April 1926 issue of Commercial Motor, the company operated a fleet of 9 of these steam waggons. Although specialists in meat transport, the company moved all classes of goods, and served an area covered by a radius of roughly 100 miles from Trafford Park, “within which is concentrated one-half of the population of England and Wales.”
The Sentinel company had its origins in Alley & MacLellan, founded in 1875 and based at Sentinel Works in Polmadie, Glasgow. The company produced steam waggons from 1905, and in 1906 introduced the 5-ton vertical-boiler waggon with 2-cylinder undertype engine (under the chassis, as opposed to the overtype used on the classic traction engine) and chain drive.
This design was so successful that it remained in production essentially unchanged until the launch in 1923 of the Sentinel Super. From Commercial Motor we discover that the waggons in our Snapshot were acquired in 1921.
These vehicles could compete with the railways in delivery of fresh meat in good condition. To quote the article again: “It is no uncommon circumstance at Trafford Park for an urgent call for meat to be received at mid-day from Birmingham, which is 80 miles away, for the vehicles to be loaded up and leave the cold stores at 2 p.m. and for them to reach the Midland centre at 11 p.m. the same day. This, of course, permits the meat to be placed on sale in excellent condition at five o’clock on the following morning.”
At the heart of this capability lay the Sentinel boiler. It was carefully designed for use in a steam waggon: compact, easy to handle whilst driving, able to cope with feedwater of poor quality and simple to maintain for a small operator without access to a major locomotive works. It was vertical, which reduced the effects of tilting during hill climbing or running on uneven roads. Its compactness left room in the cab for the crew, controls and coal bunker, and as much as possible of the waggon’s overall length available for the useful load.
The watertube boiler was top-fired – fuel was simply poured down the central chute, with no need for a side firedoor.
An unusual feature of the Sentinel boiler was the “exhaust drying box”, a small reheater in the upper part of the boiler flue heated the exhaust steam to avoid it condensing into a visible white plume. It was a requirement of the Highways and Locomotives Act 1878 that engines should “consume their own smoke”.
There is no sentiment in commerce and industry. Well-designed steam waggons continued to be used in quantity right up to World War 2 – because they were the best machine for the job. And these Sentinels were some of the finest.