88 AGRICULTURAL ENGINEERING 



that do very creditable and economical work. Tile ditching 

 machines have either a power-driven wheel or an endless 

 chain, on which knives and buckets are attached for loosening 

 the soil and carrying it above the surface where it may be 

 deposited on a conveyor and carried to one side of the ditch. 

 The machine must be so constructed that the cutting 

 mechanism can be easily raised or lowered and equipped 

 with sights or gauges which indicate clearly the depth the 

 machine is digging. Steam and gasoline engines are used 



Fig. 55. A large tile ditching machine at work. 



*o furnish the power. Traction gearing drives the whole 

 machine forward at the proper speed, which, in favorable 

 soil, may be as much as 175 feet per hour when digging four 

 feet deep or less. 



The great difficulty in the past has been to design a 

 machine which would dig a ditch to grade in soft soil having 

 but little supporting power. This has been overcome to a 

 great extent by providing caterpillar traction wheels or 



