Renewing Valve Seats : A New Method
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A NEW method of fitting valve coat ings has recently been introduced by the Harold Andrews Grinding Co., Montague Street, Birmingham, and whilst simple in conception the method of retention seems to be most effective. The original Beatings are first of all bored out with a parallel cut about I in. deep. In the centre of this boredout portion a ring groove about 3-32 in. wide is then cut to receive a spring ring.
The new seating, made of a special grade of iron, is also recessed with a ring groove on its outside circumference and a spring ring—after the fashion of a piston ring—is so arranged that it just B38
closes up to the outside diameter of the seating piece. This assembly is then pushed home into the -cylinder block, when the ring expands so soon as it reaches its correct position and locks the two components together in the manner shown in the illustration.
So strong is the arrangement that when a load of 10 tons is applied to the seating the ensuing failure takes place in the surrounding wall of the cylinder-block casting. This must be considered to be remarkable, for only 600 lb. pressure is required to drive the seat home with the. usual interference fit between the inside diameter of the recess in the cylinder block and the outside diameter of the renewed seating.
Operators whose vehicles cover, large mileages may be interested to know that the Harold Andrews Grinding Co. specializes in the replacement of Worn parts of engines.