The two barrels or cylinders of this pump are brought together so as to occupy as little space as possible. Instead of cranks eccentrics are used having very large wearing surfaces. Each pitman has a ball at its lower extremity forming a “ball and socket” joint, which is adjustable to compensate for wear. All the bearings are Babbitted and like the last pump described the gears have cut teeth. It is belt driven.
_If there are two cranks as in the duplex power pump_ they are placed opposite to one another or 180° apart, the circle described by the crank-pin containing 360 degrees. _In the triplex pump_ this circle is divided into three equal parts of 120° each which is represented by the position of the cranks; _a quadruplex_ or two duplex pumps attached to the same shaft the cranks will be 90° apart. This arrangement effects a uniform distribution of load on the crank shaft and one of the pumps is continuously discharging at its maximum capacity.
This duplex _power_ pump should not be confounded with the “Duplex Pump” so called. The latter has two steam cylinders and two water cylinders and is double acting while the former is single acting.
The successful operation and durability of these, as of all power pumps, depends largely upon the judicious selection and application of a proper _packing to the stuffing boxes_. As for example, plaited flax dipped in a mixture of warm graphite and tallow, braided rawhide, Selden’s packing, etc., have proved by long service to have a _low co-efficient of friction_ and are not liable to cut the plungers.
_The triplex power gang pump_ is shown in Fig. 211. The engraving represents two triplex pumps bolted to one bed, and having an extended pulley shaft with pinions near each end to drive all of the pumps.
===========+========+========+========+========+======== No. | 1 | 2 | 3 | 4 | 5 -----------+--------+--------+--------+--------+-------- Size of | | | | | Plunger | 2-1/4 | 3 | 4-1/2 | 6 | 8 in inches | | | | | -----------+--------+--------+--------+--------+-------- Length of | | | | | Stroke | 2-3/4 | 3-1/4 | 4-3/4 | 6-1/2 | 8-1/2 in Inches | | | | | -----------+--------+--------+--------+--------+-------- Gallons | | | | | per Stroke | .28 | .58 | 1.96 | 4·76 | 11.08 or 1 Rev. | | | | | -----------+--------+--------+--------+--------+-------- Revolutions| | | | | per |20 to 50|10 to 40|10 to 40|10 to 30|10 to 25 Minute | | | | | -----------+--------+--------+--------+--------+-------- Size of | | | | | Suction | 1-1/4 | 1-1/2 | 2-1/2 | 4 | 5 in Inches | | | | | -----------+--------+--------+--------+--------+-------- Size of | | | | | Discharge | 1-1/4 | 1-1/2 | 2 | 3-1/2 | 4 in Inches | | | | | -----------+--------+--------+--------+--------+-------- Size of | ACCORDING TO DUTY REQUIRED Pulleys | -----------+--------+--------+--------+--------+-------- Geared | { *16 }| { *16 }| { *13 }| { *20 }| { *20 } | { 72# }| { 80# }| { 71# }| { 89# }| { 80# } -----------+--------+--------+--------+--------+-------- Pressure | 175 | 175 | 170 | 165 | 160 Pounds | | | | | -----------+--------+--------+--------+--------+--------
