Fig. 290.
Suppose that the steam piston has moved to the end of its stroke, the auxiliary valve, which, as stated above, is connected to the piston rod, is shifted. This releases the steam from one end of the steam chest, D, through port, K, to exhaust, L. The steam pressure at the opposite end of the steam chest causes the steam valve to slide to opposite end of the steam chest, thus reversing the motion of the main steam piston.
To set the auxiliary valve, remove the pendulum or tappet lever, X, and the cap or bonnet, O, and take out the auxiliary valve, E. With a straight edge and scriber indicate the working edges on the end of the valve, and mark the edge of the port on the valve seat so that it can be seen when the auxiliary valve is in its proper place. Replace the valve, and the pendulum lever, omitting the bonnet.
Fig. 291.
Push the steam piston to one end of the stroke, then swing the pendulum lever toward the end of the cylinder corresponding to the piston, and until the auxiliary valve uncovers the port leading to the end of the valve chest farthest from the piston. Connect the horizontal rod to the bottom of the pendulum lever. Then remove the lever from the auxiliary valve stem and replace the bonnet and pendulum lever, shown by dotted lines. The length of the stroke may be regulated by raising or lowering the end of the horizontal rod in the slotted lower end of the pendulum lever. Lowering the rod produces a longer stroke, and raising it shortens the stroke.
THE BURNHAM.
Fig. 292.
The accompanying engravings illustrate the cylinder valves and valve motion of the Burnham single cylinder pump. [Fig. 294] is a plan of the main cylinder valve face, having the same arrangement of ports as the cylinder shown in [Fig. 293].