45 pounds. It is, in fact, the well-known feed valve that has been used for many years in connection with the G-6 brake-valve, the only distinction being in the name; but, as here used, it is attached to a pipe bracket in the same manner as the B-6 valve. To adjust this valve, remove the cap nut on the end of the spring box; this will expose the adjusting nut by which the adjustment is effected.

The pipe bracket upon which the C-6 Reducing Valve is mounted is the same as is used with the B-6 feed valve-the crossed-passage bracket, in the No. 6 equipment, and the valve turned down in its proper position.

MAIN RESERVOIR FEED-VALVE
PRESSURE
PRESSURE

ATMOSPHERE

WASTE STEAM AT
ATMOSPHERIC
PRESSURE

FIG. 45. The SF-4 Pump Governor. The modified duplex pumpgovernor used in the No. 6 E T locomotive-brake equipment. MR-main-reservoir pipe, direct; ABV-pipe to automatic brakevalve; FVP-branch of feed valve pipe; B-steam pipe to boiler; P-connection with air pump; W-waste-pipe connection.

1909, by The Norman W. Henley Publishing Co.

MR

THE "S-F4" PUMP GOVERNOR.

The duty of any pump governor is to control the steam pressure that operates the air pump so that the pressure in the main reservoir will not exceed a given figure. With the single-top governor that figure is invariable; but with the duplex, or double top, S-F PUMP GOVERNOR, used in the No. 6 E-T equipment and illustrated sectionally in Fig. 45, the action of the pump is so restricted as to permit a pressure being carried in the main reservoir only 20 pounds or so in excess of that in the brake pipe while the automatic brake-valve is in running or holding positions; but when the brake-valve is moved to application, or lap, positions this governor releases the pump to increase the main-reservoir pressure to the figure fixed as the maximum. To accomplish this differential regulation only one steam valve and piston are required, and these comprise the working parts of the bottom section-being exactly similar to the corresponding section of the single-top governor; but there are two tops, or regulating sections, of the S-F

NOTE. The figure 4 has no reference to the type of valve in connection with which it is used, and is only present to indicate the size, or, rather, the size of the steam pipe in which the governor is placed. The sizes of pipe connections are referred to in fractional fourths of an inch, this being understood, and only the numerator is given. A 3-inch pump governor-that is, a governor with connections for 2-inch steam pipeif of the S-F type, would be referred to as "S-F 3." Hence, the S-F4" means a one-inch governor (4-fourths).