Tilting suspension for crawler frames

Claim 1

A MOBILE ROCK DRILL SUPPORT COMPRISING: TWO PARALLEL CRAWLER ASSEMBLIES; A CRAWLER FRAME WITHIN EACH OF SAID ASSEMBLIES; REARWARD PORTIONS OF SAID ASSEMBLIES HAVING A COMMON TRANSVERSE AXIS, SAID ASSEMBLIES BEING PIVOTABLE ABOUT SAID AXIS; A TRANSVERSE FRAME PIVOTABLE ABOUT SAID AXIS, PIVOTABLY SECURED TO SAID CRAWLER FRAMES; TWO ELONGATED RIGID SUPPORT MEMBERS, RIGIDLY SECURED TO AND EXTENDING REARWARDLY AND INWARDLY FROM INTERMEDIATE PORTIONS OF SAID CRAWLER FRAMES, RESPECTIVELY, SAID SUPPORT MEMBERS BEING PIVOTABLY SECURED TO EACH OTHER; UNIVERSALLY PIVOTABLE BEARINGS MOUNTED ON INTERMEDIATE PORTIONS OF SAID SUPPORT MEMBERS, RESPECTIVELY, SAID BEARINGS BEING SLIDABLY TRANSVERSELY OF SAID SUPPORT MEMBERS; AN ELONGATED RIGID CROSSBAR MEMBER EXTENDING BETWEEN AND FIXEDLY SECURED TO SAID UNIVERSAL BEARINGS; SAID CROSSBAR MEMBER HAVING A CENTRAL TRANSVERSE BORE THERETHROUGH; PIVOT MEANS RIGIDLY SECURED TO SAID TRANSVERSE FRAME, SAID BORE AND SAID PIVOT MEANS HAVING A COMMON AXIS NORMAL TO SAID TRANSVERSE AXIS AND SAID BORE SLIDABLY RECEIVING SAID PIVOT MEANS TO PERMIT SAID CRAWLER FRAMES TO ROTATE WITH RESPECT TO EACH OTHER WITHIN THE LIMITS IMPOSED BY THE CLEARANCE BETWEEN SAID RIDIG FRAME AND SAID SUPPORT MEMBERS.