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TRENCHING AND SUBSOILING 



Description. It consists essentially of a horizontal 

 winding drum (Fig. 10), made of sheet steel and angle iron. 



Fig. 10. Grub's Horse-gin. 



It is very strong, and is set in a frame made of iron rolled 

 joist girders and T iron, easily dismounted by means of bolts. 

 Above the frame a pair of cog-wheels are interposed between 

 the pole axis and the drum axis, which according to their 

 position, allow different rates of winding to be obtained, and 

 consequently different powers of traction. A pole-socket 

 fixed on one of the vertical shafts carries the pole, the 

 frame rests on four rollers, rolling on two rolled joist 

 girders, placed flat on the ground, and serving as rails. 



This gin has three speeds. For very deep cultivation, 

 requiring great traction, the large cog-wheel is keyed on the 

 drum shaft, and the pole-socket keyed on the shaft of the 

 small pinion. In this case the traction on the cable is to- 

 the power Of the animals as 20 is to 1. For ploughing at a. 

 medium depth, the pole-socket is keyed directly on the drum 

 shaft, working independently of the cog-wheels. In this- 

 case the effort is increased ten times, as in the Beauquesne 

 machine. If the working of the land does not require so much 

 power, one may work quicker by fixing the small pinion on 

 the drum shaft, and the large cog-wheel on the shaft carry- 

 ing the pole. The effort in this case is increased five times. 

 The shifting of the cog-wheels is done very easily. They run. 

 loose on the shafts, and are engaged by means of a cotter 

 fixing them to circular plates, placed underneath and keyed, 

 on the shaft. 



