84 



INSTALLATION OF TKENCHING 



DOUBLE-EFFECT CAPSTANS. 



Finally, with the object of doing more work with one cap- 

 stan, balance-ploughs, ploughing both ways, have been tried. 

 In this class we may mention Debains' system, exhibited by 

 Tritschler at the general annual show held at Paris, 1892. 



Diagram 51 and Plate IV. show the capstan A, with two 

 bevel-pinions B and C, gearing together, and on the horizontal 

 shaft a coupling-clutch d allowing the drums E and F to be 



Fig. 51. Diagram of Debains' compound system. 



engaged alternately. The two drums are equal in diameter, 

 but of different width. On the drum E, a direct traction 

 cable winds which is fastened to the balance-plough. On 

 the drum F, which is double the width of E, the hauling- 

 back cable double the length is wound. Brakes act on the 

 flanges a a to steady the unwinding ; 'two winding guides 

 n n revolve on a horizontal axis, on which two spirals are 

 fixed, wound in opposite directions, forcing the guides m m 

 to travel right and left alternately ; each spiral is worked 

 periodically by the pins b fixed on the 

 drum. 



flanges of each 



Debains' machine is mounted on four iron discs pene- 

 trating the soil and acting as anchors. The front axle is 

 fixed by a king-bolt, enabling the machine to be turned ; a 

 small capstan G gearing with an endless screw B serves 

 for the lateral displacement. A case T may be loaded 

 with earth. 



Plate IV. shows the projection plan of the system at 

 work. The capstan A, the drum F, the plough M, the 

 fixed pulley P, and its automatic anchor, provided with 



