US2494988A - Centrifugal pump - Google Patents

Description

F. COLLURA CENTRIF'UGAL PUMP Jam. W W5@ 5 Sheets-Sheet 2 Filed June 20, l947 J! W, 1950 F. COLLURA CENTRIFUGAL PUMP 5 Sheets Sheet 3 Filed June 20, 1947 N mmvroza. c/zazmm Q7/1422;

A R U L L O C F CENTRIFUGAL PUMP 5 Sheets-Sheet 5 Filed June 20, 1947 WUMMEMM Patented Jan. 17, 1950 CENTRIFUGAL PUMP Francesco Collura, New York, N. Y., assign: to

Waterous Company, St. Paul, Minn, a corporation of Minnesota Application June 20, 1947, Serial No. 755,852

19 Claims.

1 My invention relates to an improvement in centrifugal pump wherein it is desired to provide a simple and efficient type of pump and drive mechanism therefor.

Centrifugal pumps of the type used on fire fighting ap a atus and the like are usually mounted with their impellers rotatable upon a horizontal axis or on separate horizontal axes. The impeller shaft is usually driven from a propeller shaft which extends substantially horizontally somewhat below the level of the truck chassis upon which the pump is mounted. In order to drive the impeller shaft from the propeller shaft of the truck it is necessary to provide a gear train between these two shafts. Because of the substantial spacing between these shafts, this structure involves certain dimcultles. In the first place if a gear on the propeller shaft directly engages a gear on the impeller shaft, the two gears must be of large diameter. As a result the peripheral speed of the gears is extremely high. On the other hand if idle gears are provided between the two shafts, separate idle gear shafts and mountings must be provided and care must be taken to mount these gears of proper size to provide several rotating speeds. Furthermore in order to change the speed ratio between the propeller shaft and the impeller shaft, it is necessary to provide either adjustable idle gear shaft supports or else to change the positions of the idle gear shafts for each change in speed ratio. The use of adjustable idle gear shaft supports is usually impractical and increases the cost of production of the pump out of proportion to the advantage gained. Asa result different pump-castings are usually required when the gear ratio between the impeller shaft and the propeller shaft is changed.

It is an object of the present invention to provide a pump having its impellers mounted upon a vertical impeller shaft. This vertical impeller shaft is connected to the propeller shaft by a pair of bevel gears. As a. result the rear ratio between the two shafts may be varied by merely changing the sizes of these two sears. As a result the same pump castings may be used in producing'pumps having a variety of impeller speed ratios.

A feature of the present invention resides in I the fact that the vertical impeller shaft provides a convenient means of taking up the space between the top of the truck chassis on which the pump is mounted and the propeller shaft which is located substantially below the chassis. This drive may be accomplished through the use of but a; single pair of gears and thus the necessity of 2 idle gears or high peripheral gear speeds may be eliminated.

A feature of the present invention resides in the fact that the pump may be mounted upon the chassis and various parts of the pump may be repaired or replaced without dismounting the pump from the truck. For example the gear ratio of the pump may be changed whilethe pump is mounted upon the chassis. Furthermore various other parts of the pump may be removed without disturbing the pump mounting. I

A feature of the present invention resides in the provision of a pump inwhich the impeller shaft is positioned at right angles to the drive or propeller shaft. Because of this construction the pump may be manufactured without dimculty, as in the past it has usually been necessary to watch closely the spacing of the various shafts upon which the drive gears were mounted.

A feature of the present invention resides in the fact that the impellers and wear rings associated therewith may be removed readily when the top of the pump casing is removed, thereby obviating the necessity for dismantling the pump or removing the same from the chassis to repair or replace these elements.

A feature of the present invention resides in the fact that the intake and discharge manifolds may be cast integrally in a. single casting, thus eliminating the necessity of having several castings of considerable length.

A further feature of the present invention resides in the provision of a transfer valve which is accessible for repair or replacement when the upper housing casting is removed. The transfer valve is located in the lower impeller housing casting which is the casting secured to the pump chassis supports. As a result the transfer valve can be repaired or replaced without removing the housing from the chassis.

A further feature of the right angle drive construction resides in the fact that different gear ratios between the impeller shaft and the propeller shaft may be obtained on a single set of gear centers. This has usually been impossible with a construction of this sort employing parallel.

of the bevel gears and the clutch stretcher may amp 3 be removed. Repairs and replacements within the gear housing may thus be made with a minimum of difiiculty.

An added feature of the present invention resides in the provision of a pump having generally parallel inlet and outlet manifolds which are connected together in a unitary casting, thus simplifying the construction and assembly. My pump is so constructed that the water changes direction but a few times, thus increasing the efficiency of the pump.

Further features of my invention lie in the silent operation of the pump when using spiral bevel gears, automatic lubrication of the pump.

porting the main drive gear, and other important structural features which will be more clearly apparent in the description of the invention.

These and other objects and novel features of my invention will be more clearly and fully set forth in the following specification and claims.

In the drawings forming a part of my specification:

Figure 1 is a top plan view of my pump showing the construction thereof.

Figure 2 is a side elevational view of the same.

Figure 3 is an end elevational view, partially in section showing my pump construction.

Figure 4 is a sectional view vertically through the pump showing the construction thereof.

Figure 5 is a sectional view through the pump transmission the section being taken through the vertical impeller shaft at right angles to the section shown in Figure 4.

Figure 6 is a transverse section through the pump, the position of the section being indicated by the line 6-6 of Figure 4.

The pump A is particularly designed for use as a fire pump or similar portable supported pump and is shown as including a manifold which provides an integral inlet manifold II and an outlet-manifold l2. These manifolds II and I2 are combined in a single unitary casting and are generally parallel throughout their length, although the ends l3 of the inlet manifold M are off-set so as to space the tubular passages to permit valves or the like to be fastened to the ends thereof. Integral flanges l4 are provided at the opposite ends of the manifold III to provide a simple means of attachment with connecting tubular members, valves, or the like. The manifold I0 is provided at points spaced from opposite ends thereof, with brackets l5 having a flat undersurface on which the manifold It may rest. The pump is supported from these two brackets IE on the manifold l0 and from a third suspension point on the opposite side of the pump which will be later described. The brackets [5 may be fastened to the chassis of the fire truck or to any other suitable means of support. The manifold preferably extends transversely of the truck chassis.

Between the ends of the manifold I0, I provide an inclined mounting plate l8 which is angularly supported upon the manifold l0 and which forms a means by which the manifold may be connected to the pump body. As best illustrated in Figures 1 and 4 of the drawings, three apertures are provided in the plate l6. One aperture |1 through the plate It communicates with the intake aperture Two spaced apertures l9 and through the plate It communicate with the outlet manifold l2. These apertures 1, l9, and 20 form the only communication between'the'pump and the I inlet and outlet manifolds. r

The pump A includes a body portion 2| including a substantially vertical sleeve 22 having an outwardly extending peripheral flange 23 at the lower extremity thereof. A partition 24 is provided within the sleeve 22. An inclined attaching plate 25 is secured to one side of the body member 2| and integral therewith. This attaching plate 25 is designed to overlie the similar plate I5 of the manifold l0 and the plates l6 and 25 are secured together by any suitable means such as bolts or cap screws 26. The aperture I1 in the plate It communicates with a similar aperture 21 in the plate 25 which communicates with the passage 23 leading to that portion of the body 2| above the partition 24. Above the passage 29 and spaced above the partition 24, I provide a second partition wall 30 having an axial aperture therein which is lined with an angular wear ring 3|. The portion of the body member 2| above the partition 30 is cast to provide the volute 32 and the lowermost of two impellers which will be later described. The body 2| is increased in thickness at 33 to accommodate the volute 32 and the upper end of the body 2| is provided with a peripheral flange 34 by means of which the body member 2| may be connected to the cap portion of the casing.

An axial upwardly projecting boss is provided 0n the partition 24. This boss 35 is mm has a hub 4| which engages against a shoulder 42 on the shaft 31 and is held in place thereby. The impeller 40 is made in the usual manner and includes a pair of disc-like sides in spaced relation connected by curved vanes or plates not specifically illustrated in the drawings. Water or other liquid enters the impeller 40 through the intake passage near the hub 4| of the impeller and between the shaft 31 and the flange 43 of the impeller. The flange 43 is designed to engage within the wear ring 3| and is guided thereby. The liquid entering the impeller intake is forced into the volute 32 and through a suitable discharge passage which will be later described in detail. v

A spacer block 44 is provided with a peripheral flange 45 engaged in an annular groove 46 in the casing portion 2|. The spacer block 44 acts as a spacing member between the lower impeller 40 and the upper impeller 41. The impeller 41 is mounted upon the shaft 31 and is held in place by asuitable lock nut means 49. Drainage may take place through the Spacer block 44 in the manner which will be later described in detail.

The cap portion 50 of the pump casing is provided with a peripheral flange 5| thereupon designed to rest upon the peripheral flange 34 of the casing portion 2| and tube secured thereto by bolts 52 or other suitable means. The cap portion 42 is enlarged in cross section near its periphery at 53 so as to accommodate the volute 54 of the upper impeller 41. A partition 55 is formed in the casing portion 50 above the level of the volute 54 and this partition is provided with an axial aperture lined with a wear ring 56. The impeller 41 is provided with a flange 51 encircling its axial intake which may engage the wear ring 56- and be guided thereby. The wear rings 3! and 56 are designed to form the running seal between the impellers and the portions of the casings enclosing the entrance ends thereof.

' The casing portion 50 is provided with a closed top 59 spaced above the partition 55. This construction provides a chamber 60 above the impeller inlet which may be secured either to the inlet manifold II or to the volute 32 of the lower impeller 40 as will be later described. A passage 6i within the casing portion 50 communicates with a cooperable passage 62 in the top of the body portion 2i. The passage 02 is reduced in area at 33 to form a seat for a flap valve 64 pivotally supported in the body portion 2i. When the flap valve 34 is in the closed position illustrated in Figure 4, the chamber 60 is not in communication with the intake manifold il, but when this flap valve 64 is open, water may flow from the inlet manifold M both into the chamber 05 between the partition 24 and the intake of the lower impeller 40 and into the chamber 30 communicating with the intake of the upper impeller 41.

It will be noted that apertures 66 are provided in an axial direction through the hub of the impeller 47 and similar apertures 81 are provided in an axial direction through the hub of the lower impeller 40. A passage 09 is provided through the spacer block 44 to permit water to drain from the top impeller into the bottom impeller. A check valve I0 is provided in the passage 69 so as to close the passage 39 when the pressure in the upper impeller 41 exceeds the pressure in the lower impeller 40. However, when the impellers are at rest, liquid may drain downwardly through the impellers and into the intake manifold II.

A transmission housing II is provided with a peripheral flange I2 thereupon designed to bear against the flange 23 and be secured thereto by cap screws I3 or other suitable means. The housing II includes an upwardly projecting boss I4 which has an axial opening therethrough to accommodate shaft supporting bearings I5. A shoulder I6 at the lower end of the bearing supporting aperture engages beneath the lowermost bearing I5, while a plate 11 overlies the uppermost of the two bearings to hold the bearings in proper position. The plate I! is held in place by cap screws I9 or the like. A liquid seal 80 is provided between the plate I! and the shaft 31. A finger ring Si is provided on the shaft 31 immediately above the plate I9. The flinger ring BI is pro.- vided' with a downwardly directed peripheral flange 82 which encircles an upwardly extending ring-shaped flange on the plate. 'I'I so as to form an effective seal for preventing liquidfrom entering the bearings. The two bearings 15 are clamped between a shoulder formed by an enlarged diameter portion 83 of the shaft 31 and a clamping nut 84 which holds the bearings properly positioned on the shaft. The bearings 15 form opposed thrust bearings so as to compensate for any axial thrust of the shaft as well as to support the shaft for rotary movement.

A sleeve or ring 85 is supported within the housing portion II by means of spokes B6. The ring 85 slidably engages the outer race of the bearing 81 mounted on the shaft 31. The inner race of the bearing 81 is clamped between the hub of a worm wheel 89 and the hub of a bevel gear 90 and is held in place thereby.

The worm wheel 99 is in engagement with a worm gear 9! mounted on a transverse shaft 92 extending transversely through the gear housing.

6 This shaft 92 extends through a. suitable packing joint 93 in the side of the housing II and forms a means of driving a tachometer or the like. 1 The bevel gear is engaged with a suitable cooperable bevel gear which will be later described in detail.

It will be seen that the shaft 31 is supported by the bearings I5 and is guided by the bearing 81. A hearing sleeve 08 within the spacer block 44 also guides the shaft 31 between the impellers 40 and 47.

The transmission housing II includes a pair of opposed apertures 93 and 94 which are arranged on opposite sides of the housing in horizontal alignment. A plate 95 is secured by cap screws 96 or other suitable means in the aperture 94 to form a closure therefor. A sleeve 9'! is integral with the closure plate 95 and supports a pair of spaced bearings 99 which support the driven shaft I00. The driven shaft I00 may be spline connected to any driven element, such as the rear wheels of asupporting truck. A nut MI is threadably engaged on the driven shaft I00 to clamp the inner races of the bearings 99 together and against an enlargement I02 on the shaft I00. A bearing retainer sleeve I03 is secured to the sleeve 91 by cap screws I04 or other suitable means and encloses the sealing element I05. This sleeve I03 clamps the outer races of bearings 99 against a shoulder 98 on the sleeve 91.

A clutch member I05 having internal gear teeth is provided on the inner end of the driven shaft I00. The outer periphery of the clutch member I06 is such that this member may be removed through the aperture 94 if desired. The clutch member I06 includes an axial socket containing a ball bearing II" which supports the extremity I09 of the drive shaft IIO. Thus the shaft IIO may rotate relative to the driven shaft I00 if desired. The shaft H0 is extremely splined at ill for engagement with a suitable source of power supply such as an internal combustion engine. No priming pump is provided. Priming of the pump is by the intake or exhaust of the internal combustion engine through the opening at the top of the casing 50.

A plate I I2 is secured to the housing 1| in position to close the aperture 93. The plate H2 is held in place by cap screws I I3 or-any other suitable means. The plate II2 includes an integral sleeve II4 which supports a double ball hearing or thrust bearing H5. The inner races of the bearing I'I-5 are secured between the enlarged diameter portion II6 of the shaft H0 and a nut I ill on a threaded portion of the shaft. The outer race of the bearing H5 is clamped between a shoulder II 9 on the extremity of the sleeve H4 and a portion of the bearing retainer sleeve I20 which is secured to the plate M2 by cap screws I2! or other suitable means. The sleeve I20 extends beyond the nut III and encloses a seal I22 about the shaft III.

A sleeve I23 is mounted upon the enlarged diameter portion I I6 of the shaft IIIO and is supported by needle bearings I24. This sleeve is provided with a peripheral flange I25 on one end thereof which is bolted or otherwise secured to the bevel gear I26 which is gear connected'to the bevel gear 90. Splines or teeth I2'I are provided on the other end of the sleeve i23 which are engageable with internal teeth I29 of the slidable clutch member I30.

The clutch member I30 is spline connected to the drive shaft H0 and is slidably engageable 75 either with the teeth :21 of the sleeve m and with the internal teeth of the clutch member I05. In Figure 4 of the drawings the clutch member I90 is shown in an intermediate position, in which case the drive shaft H is neither connected to the pump impeller shaft or to the driven shaft I00. If moved to the left from the position illustrated in Figure 4, the internal teeth I29 of the clutch member I30 will engage the teeth I21 and the impeller shaft 31 will be driven from the drive shaft IIO through the meshing bevel gears 90 and I25. On the other hand if the clutch member I30 is moved to the right from the position indicated in Figure 4 of the drawings, the external teeth I3I thereof will engage the internal teeth of the clutch member I and the drive shaft IIO will be operatively connected to the driven shaft I00.

In order to shift the clutch member I30 into the intermediate position shown, or into either extreme position described, I provide a shifting .fork I32 which is movable in a direction parallel to the axis of the shafts H0 and I00. This shifting fork I32 is best illustrated in Figure 6 of the drawings and includes an arm I33 provided with a hub I34 at one extremity thereof, the bifurcated or forked end I32 being at the opposite end thereof. The hub or sleeve I34 is secured to a shaft I35 extending through a packing gland I35 in the wall of a removable plate I38 on the transmission housing secured to the casing by cap screws. The shaft I35 is supported by an inwardly extending boss I31 and by a portion I39 of the plate I38 adjacent the packing gland I36. Longitudinal movement of the shaft I35 will act to shift the clutch member I 30 to selectively drive the impeller shaft 31 or the driven shaft I00. The shaft I35 is held in adjusted position by the spring urged ball arrangement shown engaging the shaft in Figure 5 of the drawings or by an other suitable means.

The transmission housing TI is provided with a wall I40 of substantial thickness on the side of the casing opposite the manifold I0. This thickened wall I40 acts to support a stubshaft I or other supporting element which may be connected in any suitable way to the truck chassis. As a result the pump A is supported to the chassis from one point on one side of the pump and by the two brackets I5 on the opposite side of the pump, thereby providing three point suspension for the pump.

With reference now to Figures 1 and 4 of the drawings, it will be noted that the intake manifold II is connected to the intake chamber 55 below the lower impeller 40 through the passages 21 and 29 and is also connected to the intake chamber 60 above the upper impeller 41 through passages GI and 52. The flap valve 64 may separate the intake chamber 60 from the lower intake chamber 65 if the pressure in the chamber 50 exceeds that of the pressure chamber 55. The flap valve 64 is shown in Figure 1 of the drawings as being supported by pivotal supports I42.

The volute 02 of the lower impeller 45 is connected to a tangentially extending passage I42 which branches to form a curved passage I44 and an intersecting passage I45. Both of the passages- I44 and I45 lead to a transfer valve I46 pivotally supported in the cap portion 50 of the 'pump casing and providedwith a vertically extending operating shaft I41 extending through the casing. The curved passage I44 is designed to direct liquid in a path which extends at right angles to the branch passage I45. A passage I49 is arranged in opposed relation to the branch passage I45 and leads to the aperture 20 in the plate I5, which aperture forms a connection with the outlet manifold I2. The body of the transfer valve I46 is provided with a passage I50 therethrough which may be rotated to connect the passages I45 and I49 and to close the end of the curved passage 44. An upwardly inclined passage I5I is provided in the body portion 2i of the pump in opposed relation to the end of the curved passage I44. Accordingly the transfer valve I48 may be turned so that the passage I50 therethrough provides a communicating connection between the passages I44 and I5I. The transfer valve closes communication between the passages I45 and I49. The operation of my pumpis believed obvious from the foregoing description. Water or other liquid enters. the intake manifold II and flows into the lower intake chamber and is drawn through the impeller 40 into the lower impeller volute 32. If the transfer valve I45 is positioned for parallel operation of the two impellers, fluid is forced'through the branch passage I45, the valve passage I50 and the outlet passage I 49 to the outlet manifold I2. As the pressure inthe intake chamber 60 does not exceed that in the intake chamber 65, the flap valve 34 opens and allows water to be drawn into the upper impeller 41 and into the volute 54. The volute 54 is connected to an outlet passage I52 in the cap portion 50 and the body portion 2I of the pump, which lead to the aperture I9 forming a communication with the outlet manifold I2. Thus both impellers force liquid into the outlet manifold I2 in parallel relation.

In the event it is desired to provide series operation of the impellers, the transfer valve I45 is rotated to communicate the curved passage I44 with the inclined passage I5I, leading to the passage 6| above the flap valve 54. Liquid is then drawn from the chamber 65 through the lower impeller 40 and is forced thereby through the volute 32 through the passage I43, the curved passage I44, the passage I50, through the valve I45, and the inclined passage I5I so that pressure in the intake chamber 50 exceeds that in the lower intake chamber 65. This pressure differential causes the flap valve 54 to close, thus separating the chambers 65 and 60 and exposing the upper intake chamber 50 to the full" outlet pressure of the lower impeller. This liquid is then urged by the upper impeller 41 through the volute and the outlet passage I52 to the outlet manifold I 2.

In the preferred mounting of my pump, the manifold I0 extends transversely of the truck chassis, the brackets I5 resting upon the opposite sides thereof. A suitable support is also provided on the chassis engageable with the pump housing on the side thereof opposite the manifold I0. This positions the transmissions of the pump somewhat below the level of the chassis in proper alignment with the drive shaft normally connecting the truck engine or the engine transmission to the differential at the rear end of the truck. Thus the pump may be interposed in the drive system by merely connecting the drive shaft IIO to the power supply source and connecting pump from the truck chassis in order to take the ump apart, as the entire pump is removable from the manifold I!) if desired. Obviously by removing the cap portion 50 of the casing the upper impeller may be removed or inspected. Further by removing the cap portion 50, the upper impeller 41 and the spacing block 44, the lower impeller may beinspected or replaced. The packing gland 39 is accessible through an aperture such as I53 in the body portion 2! of the casing and the bearing retaining plate ll and the flinger ring 82 are also open for inspection through this aperture.

The transmission may be entirely disassembled by removing the plates 95 and I I2 which close the opposed transmission casing apertures. If it is desired to drive the impeller shaft 37 at a different rate of speed relative to that of the drive shaft, it is only necessary to remove the plate II2 supporting the drive shaft IE and to change the size of the bevel gears 90 and I26. Thus the gear ratio can be readily changed when found necessary or desirable.

As illustrated in Figure 5 of the drawings, the transmission housing II is provided with a pair of spaced upwardly extending partition walls I54 and I55 having apertures I56 and I5! therethrough. These walls I 54 and I55 form reservoirs between each wall and the adjacent casing portion for containing a supply of oil. In the operation of the transmission, oil is thrown against the casing walls by the gear I26 and runs into the reservoir between the opposed walls and the partition walls I54 and I55. The oil is allowed to seep back through the passages I56 and I5! into the central portion of the crank case but during operation the level of oil in the center of the crank case is lower than the oil level in the opposed reservoirs, thereby providing the desired lubrication without excessive friction or heating.

In accordance with the patent statutes, I have described the principles of construction :and operation of my centrifugal pump, and while I have endeavored to set forth the best embodiment thereof, I desire to have it understood \that this is only illustrative thereof, and that obvious changes may be made within the scope of the following claims without departing from the spirit of my invention.

I claim:

1. A centrifugal pump comprising a lower impeller housing casting, a shaft extending therethrough in a substantially vertical direction, an impeller mounted on said shaft for rotation therewith, a spacing member secured to said casting above said impeller drain passage means through said spacing member, a shaft bearing on said spacing member, a second impeller mounted on said shaft above said spacing member, and a top casting enclosing said second impeller.

2. .A centrifugal pump comprising a pump housing, a shaft extending into said housing, impeller means on said shaft within said housing, a gear housing connected to said impeller housing into which said shaft extends, a bevel gear on said shaft within said gear housing, a closure plate on one side of said gear housing, a shaft extending through said closure plate, a second bevel gear mounted upon said last named shaft and engaging said first named bevel gear, and means connecting said second bevel gear and said second shaft for rotating the same in unison.

3. A vertical centrifugal pump comprising an impeller housing, a shaft extending thereinto on a substantially vertical axis, impeller means within said housing supported upon said shaft, a

packing gland encircling said shaft at the lower end of said housing through which said shaft extends, a gear housing suspended below said impeller housing and connected thereto in spaced relation, and flinger ring means encircling said shaft between said impeller housing and said gear housing.

4. A centrifugal pump comprising an impeller housing, a shaft extending on a substantially vertical axis through the bottom of said impeller housing, a pair of impellers supported upon said shaft within said housing, an inlet chamber within said housing below said lower impeller and a' second inlet chamber within said housing above said upper impeller, a common inlet passage connected to said intake chambers, a check .valve in saidpassage between said chambers, a

discharge manifold below the level of said impellers, a volute in said housing for each impeller, a passage connecting each volute to said discharge manifold, a lay-pass between the discharge passage of said lower impeller and the intake passage of said upper impeller, and a valve controlling the flow of fluid through said bypass to either direct fluid from the volute of the lower impeller to the intake of the upper impeller above said check valve or to close said by-pass.

5. A centrifugal pump including four main castings, the first casting comprising a lower impeller housing casting, and an upper impeller housing casting connected together, a shaft ex tending into said lower impeller housing casting, impeller means supported upon said shaft within said upper and lower impeller housing castings, a gear housing casting connected to said lower impeller housing casting into which said shaft extends, drive shaft means extending'into said gear housing casting, means connecting said drive shaft means and said first named shaft to rotate the same in unison, and a manifold casting including an elongated body having a pair of substantially parallel passages therethrough comprising inlet and outlet manifolds, and communicating passages from said upper and lower impeller housing castings and said manifold casting.

6. A centrifugal pump comprising an impeller housing, a shaft extending in a substantially vertical direction through the bottom of said housing, impeller means within said impeller housing on said shaft, a gear housing suspended from'said impeller housing into whichsaid shaft extends, a drive shaft extending into said gear housing, means connecting said drive shaft and said first named shaft to rotate the same in unison, a transverse bracket secured to said impeller housing to extend laterally therefrom, and a manifold casting secured in substantially parallel relation to said transverse bracket and see cured to said impeller housing in oppositely disposed relation to said bracket, said manifold housing having substantially parallel inlet and outlet passages therethrough, and passage means in said impeller housing and said manifold cast- 11 valve at the intersection of said one passage and said by-pass.

8. A centrifugal pump including a pair of impellers, shaft means supporting the same for rotation, case means encircling said impellers,

volutes in said casing means adjacent each of said impellers, an inlet chamber adjacent each of said impellers, an outlet manifold, a passage connecting each said volute to said outlet manifold, a by-pass branching from one of said passages and extending to cross said one passage and to communicate with the inlet chamber of the other impeller, and valve means at the intersection of said by-pass and said one passage.

9. A centrifugal pump including a pump casing, impeller means therein, an inlet passage in said casing communicating with the inlet of said impeller, a volute passage communicating with the outlet of said impeller, and a unitary manifold including an inlet manifold connected to said inlet passage and an outlet manifold connected to said volute passage, said manifold comprising an elongated unitary casting open at both ends and including the inlet and outlet manifolds extending longitudinally thereof.

10. A centrifugal pump for use on a fire truck chassis comprising a pump housing, a shaft supported by said housing on a substantially vertical axis, an impeller on said shaft within said housing, a gear housing suspended below said pumphousing, a substantially horizontal drive shaft extending into said gear housing, bevel gears connecting said drive shaft and said first named shaft and rotating the same in unison, a volute in said pump housing encircling said impeller, elongated substantially horizontal inlet and outlet manifolds, said manifolds being arranged below the level of said impeller, and upwardly directed passages connecting the inlet of said impeller to said inlet manifold and connecting the outlet of said volute to said discharge manifold.

11. The structure described in claim and including sealing means about said shaft belo said impeller. I

12. A centrifugal pump including a substantially vertical shaft, a pair-of pump impellers upon said shaft near the upper extremity thereof, a pump housing encircling said impellers and including volutes, an inlet passage above the uppermost volute within said housing, an inlet manifold below the level of said volutes connected with said inlet passages, an outlet manifold below the level of said impellers, and outlet passages connecting said outlet manifold to said volutes.

13. The structure described in claim 12 and including a gear casing suspended beneath said pump housing, a drive shaft extending into said gear casing and gear means connecting said drive shaft and said impeller shaft.

14. The structure described in claim 12 and including drain openings through said impellers near the axis thereof through which liquid may drain downwardly through the impellers.

15. The structure described in claim 12 and in- 12 eluding a spacing member between said volutes, a drain passage through said spacing member through which liquid may drain from the upper impeller chamber to the lower impeller chamber.

18. The structure described in claim 12 and including a spacing member between said volutes, a drain passage through said spacing member, and a check valve in said drain passage, said check valve acting to close said drain passage when the pressure in the upper impeller exceeds the pressure in the lower impeller.

17. The structure described in claim 12 and including a spacing member between said impellers, a drain passage through said spacing member, and drain apertures in said impellers so that liquid within said impellers may drain downwardly into the inlet passage below the lowermost level.

18. A centrifugal pump including a pump housing, a shaft extending into said housing, impeller means supported by said shaft within said housing, a gear housing supported by said impeller housing, said shaft extending into said gear housing, a bevel gear on said impeller shaft within said gear housing, a pair of aligned shafts extending into said gear housing in substantially right angular relation to said impeller shaft, a sleeve rotatable supported upon one of said shafts, a bevel gear removably secured to said sleeve engageable with the bevel gear on said impeller shaft, a closure plate on said gear casing through which said one shaft extends, said closure plate being slidable along said one shaft, detachable means for holding said closure plate from sliding relative to said one shaft, said sleeve being slidably mounted uponsaid shaft.

19. A vertical centrifugal pump comprising an impeller housing, a chamber extending thereinto on a substantially vertical axis, impeller means within said housing supported upon said shaft, a packing gland encircling said shaft at the lower end of said housing through which said shaft extends, a gear housing suspended below said impeller housing and connected thereto in spaced relation, flinger ring means encircling said shaft between said impeller shaft and said gear housing, said flinger ring being open to atmosphere.

FRANCESCO COLLURA.

' REFERENCES crrsn The following references are of record in the file of this patent:

UNITED STATES PATENTS Date

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