In the embodiment illustrated in FIG 3, {TAIL ~ a cross plate} 20 is disposed in {HEAD ~ the blade} 29 extending parallel to the surface of the soil, and is secured to the blade 29, for example by screws 43 so that it slidably overlaps the stationary cross beam 17 
In the embodiment illustrated in FIG 3 , { TAIL ~ a cross plate } 20 is disposed in { HEAD ~ the blade } 29 extending parallel to the surface of the soil , and is secured to the blade 29 , for example by screws 43 so that it slidably overlaps the stationary cross beam 17
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH