Condensed from “Daimler 1896 – 1946” (St John C Nixon)
Charles Y. Wright was a young American agriculturist, who in 1901, became interested in Motor Cars. He considered the chief weakness of the petrol engine to be the noise it made. In those days, engine designers paid more attention to their engines doing things rather than the manner in which they did them. Provided the cam struck the bottom of the valve tappet and opened it was good enough, if it made a noise doing so, so be it, as long as it worked. Knight was not impressed with this theory. He could not see how a cam striking a valve tappet at any speed could ever be made to be a silent operation.
After studying all technical works dealing with the internal combustion engine, he came into contact with a mechanic named L.B. Kilbourne. They carried out experimental work with a plan to open and close ports at the top of the cylinder using an additional inverted piston which reciprocated 1 ½ inches, and sliding cut-offs in either side of the cylinder to time the closing of the exhaust and opening of the inlet. The complexity of this principle produced more noise than the poppet valve engine, then an idea came to him. Why not a cylinder within a cylinder? Instead of moving the heavy walls of a water jacket, why not employ cast iron liners the full length of the cylinder. These would be moved up and down over the inverted piston, using a wide ring on the bottom of the later to cover the ports at the time of compression and explosion? Experimental work started in August 1903, the first model operating successfully through the use of only one sleeve, but the gear necessary to give the proper motion was too complicated to be quiet. This gave way later to two sleeves operated by an eccentric shaft.
In the summer of 1904 Knight and Kilbourne produced a four cylinder engine with a bore of 3 ½ inches and stroke of 4 inches. This was fitted to a Panhard type car and driven for many thousands of miles without trouble.
A mutual friend brought the Knight sleeve valve engine to the attention of Daimler, and a car was shipped to England for evaluation. The Company was very impressed with the design but it was obvious that at the moment, its construction was far from perfect. Eventually, after much experimental work, the Company acquired an option on the exclusive rights of manufacture in the United Kingdom, together with the rights to export world-wide. The old type of Poppet valve engine was finally abandoned in favour of the Daimler Knight Sleeve valve engine.
No sooner was its valve system made known than it was assailed from all quarters. Hardly anyone had a good word to say for it. How were the upper sections of the sleeves going to be lubricated? What was going to happen if it was accidentally run without oil or overheated owing to lack of water? The exhaust ports were going to burn and great damage caused. Lectures were held on the ‘Silent Knight’ engines, one of the most interesting of which was given by Knight himself during October of 1908 to members of the R.A.C. Although all this controversy certainly drew attention to the Knight engine, it could scarcely be regarded as an advertisement.
It was decided, therefore, that a test should be carried out, which in point of severity would far surpass anything to which an internal combustion engine had ever before been submitted! It consisted of running two Knight engines continuously for 132 hours under close observation of the R.A.C. They were then to be removed and installed into two Daimler cars complete with five seater bodies, which were to be driven under their own power from Coventry to Brooklands for a further test of 2000 miles. They were then to return to Coventry where the engines would be removed and once again put on the test bench for another five hours brake horsepower test. Then they were to be dismantled so that their condition could be seen after the gruelling they had had, and a full report given to R.A.C. engineers.
The two engines selected were a 38 and a 22 h.p. having a bore and stroke of 124 x 130 and 96 x 130 respectively. They were bolted down to the test bench close together in one of the large engine testing shops at the Daimler Works. This section of the shop was railed off and was under the sole charge and observation of the R.A.C. officials from the start of the test to the finish. The observers kept watch day and night just as on board a ship, and periodically tested the revolution counters and spring balances to ensure that the engines were always running under full load.
Both engines were started up at 6:00am on Monday 22nd March 1909, and each completed the 132 hours on the following Saturday evening. To appreciate more clearly the severity of the test, if the larger engine had been driving a car during the whole time, with the standard gear ratios, a distance of 8252 miles would have been covered at a mean speed of 43.45 m.p.h. The smaller engine would have covered 8830miles at 48.4 m.p.h. The disparity in speed and distance between these results is attributable to the higher rate of revolutions of the smaller engine.
DETAILS OF THE 38 H.P.ENGINE.
First Bench Test.
The speed of the engine was 1200 rpm, giving a limit of 50 h.p. below which it was at no time to fall. The duration of the test was 5 days 14 hours and 56 minutes or 134 ½ hours. There were no stops incurring penalties. There were 5 stops totalling 1 hour and 56 minutes without penalty under rule 6 (2). The load was eased for 19 minutes for brake adjustments but the engine was not stopped. Average horsepower recorded was 54.3 Petrol consumed was 614.75 gallons, equal to .679 pints per horse-power hour.
On completing the first test, the engine was removed from the bench and fitted, under observation, to the chassis without any vital parts being disturbed. A standard 4-seater body was fitted and the car proceeded from Coventry to Weybridge – 112 miles. The average weight of the car and passengers was 4085 lbs or 1 ton 13 cwt 3qts and 25 lbs! The runs on Brooklands track amounted to 1930.5 miles at an average speed of 42.4.mph. The average weight of car and passengers was 3805 lbs. A distance of 5 miles was traversed in running to and from the car headquarters and the track, and with the return to Coventry made a total of 2159.5 miles. The petrol consumption on the track was 20.57 mpg and on the road 19.48 mpg. The ton-miles per gallon were 34.94 on the track and 35.97 on the road!
Final Bench Test.
On arrival at Coventry, the engine was replaced on the test bench and run for 5 hours 15 minutes during which there were no stoppages of any description; the load was eased for 15 minutes for brake adjustments. Average horsepower recorded 57.25. Petrol consumed 22.5 gallons .599 pints per h.p. hour. The Judges append the following remarks to their certificate: ‘The engine was completely dismantled, and no perceptible wear was noticeable on any of the fitted surfaces. The cylinders and pistons were found to be notably clean. The only visible wear in any part, was caused by two joint pins rubbing against adjacent parts. The ports of the valves showed no burning or wear.’
DETAILS OF THE 22 H.P. ENGINE.
First Bench Test
The speed of the engine was 1400 rpm giving a limit of 35.3 h.p. The duration of the test was 5 days 12 hours 58 minutes or 132 hours and 58 minutes. There were no stoppages incurring penalty. There were 2 stops of 17 minutes which did not incur penalty. The load was eased for 41 minutes for brake adjustments but the engine was not stopped. Average h.p. was 38.83 Petrol consumed was 476.5 gallons or .739 per h.p. hour.
The conditions were the same as for the 38 h.p. car test but with the following results. Average weight of car and passengers on the road, 3612.5 lbs or 1 ton 12 cwt 28 ½ lbs and on the track 3332.5 lbs. Distance covered on Brooklands track 1914.1 miles. Average speed 41.88mph. Petrol consumption on the track was 22.44 mpg and on the road 19.48 mpg. The ton-miles per gallon were 33.37 on the track and 31.19 on the road. Total mileage was 2243.1
Final Bench Test.
Duration, 5 hours and 2 minutes. There were no stoppages of any description, the load was eased for 1 minute. Average horsepower recorded 38.96. Petrol consumed, 18.25 gallons .749 pints per h.p. hour. The Judges append the following remarks to their certificate: ‘The engine was completely dismantled, and no perceptible wear was noticeable on any of the fitted surfaces. The cylinders and pistons were found to be notably clean. The ports of the valves showed no signs of burning or wear.’
And so began and ended a test which even today would tax the capabilities of many petrol driven engines.
(Remember, this was 1909 and the book was written in 1946!)