Grooving machine for shingles

Claim 1

IN A DEVICE FOR GROOVING WEDGE-SHAPED SHINGLES, A FRAME ASSEMBLY HAVING A SHINGLE-SUPPORTING DECK, A DRIVEN PRESSURE ROLL LOCATED NEAR ONE END OF SAID DECK, MEANS NORMALLY HOLDING SAID ROLL DOWN IN SHINGLE-PRESSING POSITION BUT ENABLING SAID ROLL TO BE RAISED AGAINST THE FORCE OF SAID MEANS, A ROTATING CUTTER SO POSITIONED THAT WHEN A SHINGLE IS MOVED OVER SID CUTTER WHILE HELD DOWN BY SAID PRESSURE ROLL IN LOWERED POSITION THE UNDERSIDE OF THE SHINGLE WILL BE GROOVED, SHINGLE THUSTING MEANS MOVABLE RECIPROCALLY OVER SAID DECK FIRST FORWARDLY IN THE DIRECTION OF SHINGLE TRAVEL AND THE IN OPPOSITE DIRECTION, LIFTING MEANS FOR SAID PRESSURE ROLL OPERATED BY SAID THRUSTING MEANS AND ACTING UPON SAID PRESSURE ROLL ONLY WHEN SAID THRUSTING MEANS HAS MOVED A PREDETERMINED DISTANCE FORWARDLY TOWARDS SAID PRESSURE ROLL AND CUTTER, SAID LIFTING MEANS BEING RETURNED TO INACTIVE POSITION BY THE RETURN MOVEMENT OF SAID THRUSTING MEANS IN THE OPPOSITE DIRECTION TO STARTING POSITION, WHEREBY, WHEN A SHINGLE IS PLACED ON SAID DECK WITH THE BUTT EEND TOWARD SAID PRESSURE ROLL AND THE THIN END NEGAGED BY SAID THRUSTING MEANS, THE THRUSTING OF THE SHINGLE FORWARDLY TOWARD SAID PRESSURE ROLL BY SAID THRUSTING MEANS WILL RESULT IN THE UNDERSIDE OF SAID SHINGLE BEING GROOVED BY SAID CUTTER AS LONG AS SAID PRESSURE ROLL IS IN LOWER POSITION AND ENGAGING SAID SHINGE, BUT, WHEN THE MOVEMENT OF SAID THRUSTING MEANS WITH SAID SHINGLE HAS CONTINUED FOR A PREDETERMINED DISTANCE, SAID PRESSURE ROLL WILL BE RAISED, DISCONTINUING THE GROOVE OF SAID SHINGLE.