974 



The Shrawardinb Tractor Trials, 1921. [Feb., 



the depth of furrow. Examples of the graphs obtained are 

 reproduced in the report : they show clearly the time taken in 

 turning at the headlands and the decreased pull as well as many 

 other details of great interest. Another instrument used was 

 the Heenan and Froude dynamometer which was employed for 

 calculating the belt horse-power. 



It had been intended to include in the trials, tests of tractor 

 implements : but neither the time available to the technical staff 

 employed nor the equipment on hand was really adequate for any 

 such purpose and in the result nothing of moment was attempted. 

 However, the opportunity given to manufacturers to exhibit 

 tractor implements both of standard type and new design was 

 a welcome one, which was calculated to assist farmers in the 

 selection of implements. 



Tractors and Implements Participating in the Trials. — Forty 

 tractors were entered for the trials and 38 actually took part : 

 of this number 11 were duplicates, and 27 different types were 

 therefore tested. Four machines were new to British Tractor 

 Trials : — The Renault, Avance, Simar and Service Garden 

 Tractor. Many of the machines seen in previous trials did not 

 enter. As contrasted with the 1920 trials the most notable 

 absentees were the cable sets : no tractor operated by steam 

 power was present. 



Tractors have not undergone any material alteration in design 

 since the 1920 trials, nor was there amongst the entries any con- 

 siderable departure from the principles which are more or less 

 generally accepted. There must, of course, be a number of types 

 since there exists such a variety of conditions of soil, and one 

 of the most interesting entries was the set of 10-18 H.P., 15-27 

 H.P. and 22-40 H.P. models constructed by the Case Tractor 

 Co. The only real departures from the commonly accepted 

 design were to be found in the Glasgow and the Avance tractors. 

 The Glasgow tractor, with its three ground wheels all power- 

 driven and of equal size, is well known for its hill climbing 

 capacity and its remarkable adhesion, while the nature of the 

 drive causes no unbalanced torque and the machine is therefore 

 deprived of any tendency to rear or reduce its wheel pressure 

 when pulling hard. The Avance tractor is a Swedish production 

 and is new to British practice, the engine being of the single - 

 cylinder two-stroke semi-Diesel (hot-bulb) type, mounted high 

 up in the fore part of the frame and driving through friction 

 clutch and gears to a pinion and toothed ring final drive. This 

 machine has many interesting features ; it can be used either as 

 a four-wheel self-contained unit with two furrow plough or as a 



