The directors of the Liverpool & Manchester company were unsure whether to use locomotives or stationary engines on their line. To help them reach a decision, it was decided to hold a competition where the winning locomotive would be awarded £500. The idea being that if the locomotive was good enough, it would be the one used on the new railway. The three judges of the competition were John Rastrick, Nicholas Wood and John Kennedy.
Eight conditions were laid down for the locomotives that entered the competition. This included the rule that the maximum weight was to be six tons. All wheels had to be sprung and the cost of the locomotive had to be less than £550. The gross weight of the train was stated to be not less than three times the engine's weight. To qualify for the first prize the locomotive had to reach speeds of 10 mph (16 kpm).
The competition began at Rainhill on 6th October, 1829. On the first day over 10,000 people turned up to watch the competitors. The locomotives had to run twenty times up and down the track at Rainhill which made the distance roughly equivalent to a return trip between Liverpool and Manchester. Ten locomotives were originally entered for the competition but only five turned up: the Rocket, Sans Pareil, Novelty, Cycloped and Perseverance.
Cycloped was owned by Thomas Brandreth, was powered by a horse walking on a drive belt. It reached speeds of 5 mph but after the horse fell through the floor of the Cycloped it was withdrawn.
Perseverance, owned by Timothy Burstall of Leith, was damaged on the way to the Rainhill Trials when the wagon that was carrying it overturned. Burstall spent the first five days of the trials trying to repair his locomotive. On the sixth day Perseverance joined the competition but after only reaching 6 mph, Burstall withdrew his locomotive. The judges decided that he should receive a consolation prize of £25.
At first there were doubts whether Sans Pareil would compete as the judges claimed that it was overweight. However, it was eventually agreed to let its inventor, Timothy Hackworth, show what his new locomotive could do. The Sans Pareil carried out eight trips and reached a top speed of just over 16 mph. After a promising start the locomotive suffered a cracked cylinder. Ironically, the cylinder had been cast by the company owned by his rival, Robert Stephenson. Despite its failure to win the competition, the owners of the Liverpool & Manchester railway decided to purchase Sans Pareil to use on their line.
Weighing only 2 tons 3 cwt, the Novelty was much smaller than the other entries. It was also the quickest and reached speeds of 28 mph during the trials that took place on the first day. It was a extremely popular with the large crowd that attended the trials was a hot favourite to win the competition. However, on the second day the boiler pipe became overheated and was damaged. To reach it for repairs, John Braithwaite and John Ericsson had to partially dismantle the boiler. The steam-tight joints had to be made with a cement which normally took a week to harden. Braithwaite and Ericsson had to go out the next day and when the Novelty reached 15 mph the joints started to blow. The damage was considerable and the Novelty was forced to retire from the competition.
The final entry was the Rocket that had been entered by Robert Stephenson. Two men who worked for the Liverpool & Manchester Railway, Henry Booth, the Secretary and George Stephenson, the chief engineer, were also involved in developing the Rocket. It was Booth who suggested using a multi-tubular boiler to produce the necessary steam to drive the locomotive.
On the third day the Rocket covered 35 miles in 3 hours 12 minutes. Hauling 13 tons of loaded wagons, the Rocket averaged over 12 mph. On one trip it reached 25 mph and on a locomotive-only run, 29 mph. After studying all the evidence, the three judges, John Rastrick, Nicholas Wood and John Kennedy, awarded the £500 first prize to the owners of the Rocket. The contract to produce locomotives for the Liverpool & Manchester Railway went to the Robert Stephenson Company at Newcastle-upon-Tyne.