The latter is cast hollow and strengthened by ribs.
The pistons are provided with cast iron double self-expanding packing
rings. For preventing accidents by condensed water, spring safety
valves, ss and s1 s1, are connected to the valve chests. The valve gear,
which is arranged in the same manner for both cylinders, is actuated
by shafts, w and w1, rotated by toothed wheels as shown. Motion is
communicated from the way-shafts, w and w1, by the eccentrics, and the
eccentric rods, e1 e2 e3 e4, and the levers and rods belonging thereto,
to the short steam valve rocking shafts levers, f1 f2 f3 f4, and the
exhaust valve rocking shafts, k1 k2 k3 k4, the bearings of which are
carried on brackets above the valve chests, which, being furnished with
tappet levers, raise and lower the valves.
[Illustration: BORSIG'S IMPROVED COPOUND BEAM ENGINE. FIG. 3]
The valves are conical, double-seated, and of cast iron, and the inlet
and outlet valves are placed the one above the other, the seats being
also conically ground and inserted through the cover of the valve chest.
Both inlet and outlet valves are actuated from above, and are removable
upward, an arrangement which admits of the valves being more easily
examined than when the two are actuated from different sides of the
valve chest. To carry out this idea the inlet valves are furnished with
two guides, which, passing upward through the stuffing-box, are attached
to a hard steel cross piece, which receives the action of a bent catch
turning on a pin attached to the levers, t1, t2, t3, t4.
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