When putting heads back on the pump use ordinary _newspaper for packing, nothing thicker_, as thicker packing destroys the suction.
Prevent all leaks in suction pipe which would impair the vacuum.
The suction should furnish an uninterrupted supply to the pump, to enable the pump to throw its full capacity. Never use pipes smaller than the openings in pump.
Open all drips in cold weather to prevent freezing.
All packing boxes should be kept in order and never allowed to leak.
The illustration, Fig. 482, page 204, represents a rotary pump of the Holyoke pattern to be attached by a clutch to a line shaft—the gears, as shown, are merely to transmit the power to the impellers. The safety valve with lever and weight, shown in the cut, are designed to be attached to the discharge pipe to guard against over pressure, which might occur through the closing of valves.
Fig. 483 shows an emergency pump of the Holyoke rotary pattern. It is of the same general design as the one previously alluded to. It is driven directly from the line shaft by friction gearing instead of toothed wheels. The hand wheel attached to the end of a screw is used to press the smaller friction wheel against the larger and thus transmit the power to drive the pump.
This mechanism is not liable to injury by being thrown instantly into gear in case of fire, as would be the case if gear wheels were used.
These pumps are largely used in mills located in the Eastern United States, _as they may be started up in a few moments at full speed_ without slowing down the engine or motor driving the line shaft.
The shaft bearings are all made of large proportions to avoid heating and excessive wear when suddenly put under full load.
Figs. 484 and 485 are views of a _rotary pump driven by steam_ and largely used for fire apparatus. These pumps are in general use in mills and factories, and can be installed wherever the necessary steam and water supply are available.
The pump is built on a rigid iron base plate, and is furnished with air chamber, water-pressure gauge, oil feeders and everything necessary to make it complete and ready for permanent steam and water connections. The discharge outlets can be adapted for forcing water through either pipe or hose.