Hackworth's Sans Pareil design included a return-tube boiler, and steam was exhausted by the chimney by a blast-pipe to draw the fire as fiercely as possible. Cylinders were vertical but were inverted by the pistons to drive the rear pair of wheels directly by connecting rods. The main weakness of this approach was that it effectively prevented springs being used to carry the locomotive.
At first there were doubts whether Hackworth's Sans Pareil would compete as the judges claimed that it was overweight. However, it was eventually agreed to let 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, George Stephenson.
Despite its failure to win the competition, the owners of the Liverpool & Manchester railway decided to purchase Sans Pareil and was kept in service until it was sold to John Hargreaves & Son in 1831. They leased it to the Bolton & Leigh Railway where it was used to haul goods and passengers.
Sans Pareil was rebuilt with a larger cylinder in 1837 and carried on work on the line until 1844. The locomotive was then leased to a colliery that used the locomotive as a stationary engine until 1863. The Sans Pareil was then restored by the Soho Iron Works at Bolton and in 1865 was presented to the South Kensington Museum.
(1) The Mechanics Magazine (10th October, 1829)
The Sans Pareil exhibits in its general appearance particularly in its large dimensions a near resemblance to Mr. Stephenson's engine; but is much more compactly arranged, and on account of this compactness, travels with much greater steadiness. The furnace and boiler are not placed head-and-tailwise, as in "The Rocket," but form together the main body of the engine.
The mode of generating the steam adopted in this engine is the same which Trevithick introduced as far back as 1804, and possesses all the merit voice has been generally conceded to, that plan, without exhibiting any effort to obviate the objections that have been as generally made to it. The furnace and boiler are of simple construction, and of unquestionable efficiency; but their great size, and the large supply of fuel and water they require, render them but ill-adapted to the purposes of a locomotive engine.
(2) The Mechanics Magazine (17th October, 1829)
On 13th October Mr. Hackworth's engine, "The Sans Pareil," was pronounced to be this day ready to exhibit its powers. We were informed that, on weighing it, the judges found it to exceed by two or three hundred-weight the maximum of six tons; it was, nevertheless, allowed to start to do 70 miles, in the same manner as "The Rocket," with three times its great weight attached to it . It was soon manifest that a very powerful competitor had entered the field. For two hours "The Sans Pareil" kept going with great regularity, and during that time completed upwards of 25 miles. It went occasionally, when at its utmost speed, a mile in 4' 10" and 4' 17", being at the rate of nearly 15 miles an hour. While thus bidding fair - if not to win the prize, at least to come in second best - a similar accident happened to it as befell "The Novelty;" one of the feed pipes burst, and it was rendered for the time incapable of proceeding.
(3) Samuel Smiles, The Lives of George and Robert Stephenson (1857)
The Sans Pareil was not ready until the 13th; and when its boiler and tender were filled with water, it was found to weigh 4 cwt beyond the weight specified in the published conditions as the limit of four wheeled engines, nevertheless the judges allowed it to run on the same footing as the other engines.
Neither in construction nor in principle was the engine deficient but circumstances compelled me to put that confidence in others which I found with sorrow was but too implicitly placed, as the defect was a cylinder which failed from its defective casting.