1J4 



COMBINED PORTABLE ENGINE 



Systems with two traction drums, drawing a balance- 

 plough backwards and forwards, are in use. One of the 

 cables passes over a pulley fixed on the opposite headland. 

 Fig. 72 represents one of these at work. In this system 

 the two winding drums are of equal diameter, but that 

 winding the return cable is wider as it has to accommodate 

 double the length of cable. 



COMBINED PORTABLE ENGINE AND WINDING DRUM. 

 Stationary System. 



When the system is fixed stationary in a given position 

 in the field, the old Howard system (shown in Figs. 73 and 

 74) may be adopted. The two drums run loose on a shaft fixed 

 on an eccentric ; a lever allows the cog-wheel of each drum 

 to be raised and thrown into gear with the pinions keyed on 

 the intermediate shaft, carrying the belt pulley. When the 

 drum is thrown out of gear, its flange rests on the shoe of 

 the brake, which is kept in position by a counterpoise (not 

 shown in this figure). The frame of the drum is carried by 

 two wheels. The shafts of the frame are attached to the 

 rear of the engine, the cables passing under the platform 

 where the engine-driver stands, then over the two pulleys 

 fixed on a special frame bolted on the forecarriage of the 

 machine. Plate IX. shows the working installation. 



Fig. 73. Howard's Winding Drum worked by a portable engine. 



