Self-propelled post driver

Claim 1

A SELF-PROPELLED POST DRIVER COMPRISING, A SELFPROPELLED TRACTOR HAVING A CHASSIS, AN ERECT ELONGATED MAST, SWIVEL MEANS MOUNTING THE LOWER END OF SAID MAST ON SAID TRACTOR CHASSIS FOR UNIVERSAL MOVEMENT WITH RESPECT THERETO, CONTROLLABLY EXTENSIBLE ELONGATED ELEMENTS HAVING THEIR LONGITUDINAL AXES DISPOSED IN SUBSTANTIALLY VERTICAL PLANES ORIENTED SUBSTANTIALLY AT RIGHT ANGLES TO ONE ANOTHER AND PASSING THROUGH THE LONGITUDINAL AXIS OF THE MAST, EACH OF SAID ELEMENTS HAVING ONE END PIVOTALLY CONNECTED TO THE MAST ABOVE THE LOWER END OF SAID MAST AND THE OTHER END PIVOTALLY CONNECTED TO THE TRACTOR CHASSIS FOR ADJUSTABLE PIVOTAL MOVEMENT OF SAID MAST WITH RESPECT TO THE TRACTOR ABOUT THE SWIVEL MEANS IN TWO SEPARATE ERECT PLANES, ONE TRANSVERSELY OF THE OTHER INTERSECTING AT THE SWIVEL MEANS, A BOOM, MEANS SECURING SAID BOOM TO SAID MAST AT AN ANGLE OF 90* WITH RESPECT THERETO, A TROLLEY, MEANS MOUNTING THE TROLLEY FOR MOVEMENT ALONG THE LENGTH OF THE BOOM, A POST DRIVING UNIT CONNECTED TO THE TROLLEY, MEANS MOUNTING THE POST DRIVING UNIT FOR ROTATION WITH RESPECT TO THE TROLLEY ABOUT A DRIVING AXIS PARALLEL TO THE LENGTH OF THE MAST, AND SELECTIVELY OPERABLE BRAKE MEANS FOR FIXING THE TROLLEY ANYWHERE ALONG THE LENGTH OF THE BOOM AND FIXING THE POST DRIVING UNIT IN ANY ANGULAR POSITION ABOUT SAID DRIVING AXIS, SAID POST DRIVING UNIT INCLUDING A PNEUMATICALLY ACTUATABLE JACK HAMMER, A CAGE ARRANGED TO BE DRIVEN BY SAID HAMMER, AND MEANS GUIDING SAID CAGE FOR MOVEMENT IN SAID UNIT IN A DIRECTION PARALLEL TO SAID DRIVING AXES.