THE INTERNAL - COMBUSTION TRACTOR 101 



This stops the traction gearing when the clutch is thrown off, 

 the two actions being performed in concert. A band-brake, 

 operating on a drum on the differential shaft or the rear axle, 

 is another successful device. 



TRACTION WHEELS 



The high and fairly narrow wheel, 18 to 30 niches wide and 

 70 to 96 inches in diameter, and of sufficient strength to en- 

 dure ordinary service, is apparently the most popular for gas 

 tractors, judging from recent design. Extension rims of 10 

 or 12 inches are provided in most cases for use in soft ground. 

 The wheels are usually of the built-up construction. This 

 consists of -a steel tire plate to which the cleats are attached; 

 round or flat steel spokes; and a cast-iron hub into which the 

 spokes are either riveted, cast or screwed. The spokes are most 

 often arranged radially, are occasionally on a tangent, and even 

 rarely are continuous, extending star-fashion, clear across the 

 wheel on opposite sides of the hub. The spokes may be stag- 

 gered i. e., from the outside of the spokes are frequently 

 upset to "T" shape so that two rivets may pass through the 

 head of the spoke and the tire. Flat spokes are sometimes 

 bent to fit the tire and then riveted, this being a weaker con- 

 struction. In some cases the end of the spoke is flattened out 

 like a paddle, and this riveted to the vertical flange of an angle 

 or channel iron which has been put on to reinforce the tire. 

 The round spokes sometimes extend through the tire from the 

 outside and are screwed into the hub. This holds the tire to, 

 instead of away from the hub, making what is known as a 

 tension spoke in contrast to the compression spoke usually 

 employed. 



The best type of grouter is a very unsettled problem. The 

 most common form is a V-section made of cast or malleable 

 iron. These may be attached parallel with the axle, or at an 

 angle in order to faciliate self-cleaning. Grouters set at an 



