BLOWER BRAKE ADJUSTER
MANY YEARS AGO I BORROWED AN UNASSEMBLED KIT OF PARTS FOR A BLOWER BRAKE ADJUSTER FROM BOB THREDDER AND DREW THIS UP SO THAT I COULD MAKE ONE FOR MYSELF AND SELL OFF OTHERS TO DEFRAY COSTS OF MANUFACTURE.
ABOVE, YOU CAN SEE THE BRAKE ADJUSTER JUXTAPOSED WITH THE GEAR LEVER GATE. THIS PHOTO WAS TAKEN FROM AN ORIGINAL BIRKIN BLOWER. ANOTHER POINT OF INTEREST IS THE INTERLOCK FOR REVERSE GEAR, WHICH IF YOU LOOK CAREFULLY, IS MOUNTED TO THE RHS OF THE GATE. THIS MODIFICATION REMOVED THE DANGEROUS HOOKED PULL ROD WHICH COULD CATCH THE SLEEVE OF THE DRIVER AND CAUSE AN ACCIDENT. AS FAR AS I KNOW, NO FACTORY DRAWINGS EXIST FOR THESE MODIFICATIONS AS THEY WERE DEVISED BY THE BENTLEY MECHANICS FOR THE LE MANS CARS ALTHOUGH THE LE MANS CENTRE "ORGAN STYLE" ACCELERATOR PEDAL WAS DRAWN UP BY THE DRAWING OFFICE. I DISCOVERED THIS BY CHANCE YEARS AGO WHILST TRAWLING THROUGH THE BDC DRAWINGS AT THE CLUB.
ON MY RECENT TRIP TO THE FRENCH HOUSE I DISCOVERED SOME PARTS LEFT OVER FROM THIS PROJECT, SO AM ENTERTAINING THE IDEA OF MAKING TWO OF THESE BRAKE ADJUSTERS, ONE FOR MYSELF AND ONE FOR SALE.
THE ORIGINAL MECHANICS DESIGN WOULD ONLY SUIT THE "A" AND "D" BOXES AS THESE WERE THE ONES USED FOR RACING AND HAVE A DIFFERENT GEAR LEVER OUTRIGGER POSITION TO THE B BOX DERIVATIVES BUT I MODIFIED THE DESIGN SO THAT IT WILL WORK WITH ALL THE BOXES EXCEPT THE F AND G ONES. THAT IS, A,B,BS,C &D
THE ORIGINAL MECHANICS DESIGN WOULD ONLY SUIT THE "A" AND "D" BOXES AS THESE WERE THE ONES USED FOR RACING AND HAVE A DIFFERENT GEAR LEVER OUTRIGGER POSITION TO THE B BOX DERIVATIVES BUT I MODIFIED THE DESIGN SO THAT IT WILL WORK WITH ALL THE BOXES EXCEPT THE F AND G ONES. THAT IS, A,B,BS,C &D
ABOVE IS AN EXTRACT FROM THE LAYOUT THAT I DREW UP IN 1996. FOLLOWING DESIGN OFFICE CONVENTION THE FRONT OF THE CAR IS TOWARDS THE LHS OF THE EXTRACT. WHAT IS SHOWN IS A LONGITUDINAL SECTION THROUGH THE CENTRELINE OF THE CHASSIS AND THE GEARBOX CROSSMEMBERS. THE M.O. IS THAT THE QUICK ACTION BRAKE ADJUSTER REPLACES THE ADJUSTABLE LINK BETWEEN THE BRAKE PEDAL AND THE MAIN LEVER OF THE COMPENSATOR, SO THAT THE BRAKES COULD BE ADJUSTED WHILST THE CAR WAS IN MOTION. THIS IS ACCOMPLISHED BY BY MEANS OF A WIRE CABLE ATTACHED TO THE BRAKE PEDAL WHICH PASSES OVER THE TWO SMALL PULLEYS, MOUNTED IN BRACKETS ATTACHED THE THE CROSSMEMBERS, AND ATTACHED TO THE COMPENSATOR MAIN LEVER. THIS IS TENSIONED BY THE LARGER PULLEY, WHICH IS RESTRAINED BY LINKS, BEING ADJUSTED DOWNWARDS BY A SQUARE THREADED SCREW WHICH IS ROTATED BY MEANS OF A SMALL HANDWHEEL PROTRUDING THROUGH THE FLOOR. THIS EFFECTIVELY SHORTENS THE DISTANCE BETWEEN THE PEDAL AND THE LEVER, THUS TAKING UP THE WEAR IN THE BRAKE LININGS.
ABOVE IS ANOTHER EXTRACT FROM THE LAYOUT. THIS IS A COMPOSITE VIEW OF BOTH THE FRONT AND REAR PULLEYS AND BRACKETS LOOKING TOWARDS THE FRONT OF THE CAR AND SHOWS THE PULLEY BEARINGS AND SPINDLE IN PARTIAL CROSS SECTION FOR CLARITY.
THE SET OF PARTS THAT I COPIED WERE OBVIOUSLY NOT ORIGINALS AND LACKED A CERTAIN FINESSE. I WAS WORRIED BY THE LACK OF LUBRICATION TO THE PULLEY SPINDLES AND THE FACT THAT THE PULLEYS RAN STEEL TO STEEL ON THEIR SPINDLES AND LACKED BEARINGS, SO ADDED THESE ITEMS TO THE DESIGN.
ABOVE ARE SHOWN A COUPLE OF DETAIL DRAWINGS.
IN PROGRESS