US1274319A - Ship-propulsion installation. - Google Patents

Description

C. A. PARSONS, R. J. WALKER, S. S. COOK & L. M. DOUGLAS.

SHIP PROPULSION INSTALLATION.

APPLICATION FILED IULY 6. I9I6.

1 ,274,3 1 9. Patented July 30, 1918.

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C. A. PARSONS, R. J. WALKER, S. S. COOK & L. M. DOUGLAS.

SHIP PROPULSION INSTALLATION.

APPLICATION FILED JULY 6. I9I6.

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SHIP PROPULSION INSTALLATION.

APPLICATION FILED JULY 6.1916. 1 ,274,31 9, Patented July 30, 1918.

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SHIP PROPULSION INSTALLATION.

APPLICATION FILED IULY 6.19I6. 1,274,319.

C. A. PARSONS, R. J. WALKER, S. S. COOK & L. M. DOUGLAS.

SHIP PROPULSION INSTALLATION.

APPLICATION FILED JULY 6.1916.

Patented July 30, 1918.

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SHIP PROPULSION INSTALLATION.

APPLICATION FILED IULY 6. I9II5v Patented July 30, 1918.

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SHIP PROPULSION INSTALLATION.

APPLICATION FILED JULY 6. I916.

1,274, 3 1 9. Patented July 30, 1918.

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Charles cursans Robe rZJIWoLZEer Stanlc 5. 60072 Q owns ouglasgq UNITED STATES PATEN 1 OFFICE.

CHARLES ALGERNON PARSONS, OF NEWCASTLE-UPON-TYNE, AND ROBERT JOHN WALKER, STANLEY SMITH COOK, AND LOUIS MORTIMER DOUGLAS, OF WALL- SEND, ENGLAND; SAID WALKER, SAID COOK, AND SAID DOUGLAS ASSIGNORS '10 SAID PARSONS.

SHIP-PROPULSION INSTALLATION.

Specification of Letters Patent.

Patented July 30, 1918.

Application filed July 6, 1916 Serial No. 107,833.

, 'Works, Wallsend, Northumberland, England, subjects of the King of Great Britain and Ireland, have invented certain new and useful Improvements in and Relating to Ship-Propulsion Installations, of which the following is a specification.

' The present invention relates to ship pro pulsion installations of the type in which the ratio of the revolutions of a given motor tothe revolutions of the propeller it drives differs at low powers from the ratio at full power.

Such installations are described, for example, in co-pending applications for Brit-.

ish Letters Patent, Nos. 20366 of 1914 and 9570 of 1915, in which the ratio of the revolutions of .a main turbine to the revolutions of the propeller it drives differs at low powers from the ratio at full power.

The invention further consists in the improved ship propulsion installations hereinafter described.

Referring to the accompanying diagrammatic drawings:-

Figure 1 is a plan 'of a two-shaft installation having a high and low pressure turbine in'which both the turbines are operated at low powers,

Fig. 2 shows a similar installation to that of Fig. 1 with the addition of a cruising turbine.

Fig. 3 is a plan of an installation having a high pressure, low pressure and cruising turbine so arranged that at low powers the high pressure turbi'ne'is inoperative and the cruising turbine exhausts to the lower pressure turbine.

Fig. 4 is a plan of a three-shaft installation having a high pressure and two low pressure turbines so arranged that at high powers all the turbines drive their propeller shafts directly, while at low powers the high pressure turbine on the center shaft drives thewing propeller shafts while the low pressun;t turbines drive the center propeller sha Fig. 5 is a plan of a similar installation to that shown in Fig. 4 with the addition of a crulsmg turbine connected by a pinion to the pinion of the high pressure turbine and exhausting to the high pressure turbine when operating at low powers.

Fig. 6 is a plan of a two-shaft installation in which each shaft is driven at full power by a hi h pressure and a low pressure turbine, t e whole being so arranged that the high pressure and low pressure turbines which at full power drive one propeller shaft are arranged at low power to drive the other propeller shafts.

Figs. 7 to 10 show diagrammatically details of the coupling arrangement for the installation shown in Fig. 6. Of these figures, 7 and 8 show the full power connections, while Figs. 9 and 10 show the lower power connections. I

Fig. 11 illustrates a four-shaft installation in which one pair of shafts is furnished with turbines and gearing similar to that shown in Fig. 1, while the other pair of shafts is provided with turbines and gearing similar to that shown in Fig. 3.

Fig. 12 shows a two-shaft installation in which each shaft is driven at full power by a high pressure and a low pressure turbine,

while at low powers the high pressure turbine on one shaft drives through gearing the other propeller shaft while the low pressure turbine on this other shaft drives the first-mentioned shaft through gearing, the remaining turbines and gearings being rendered inoperative by means of clutches.

Fig. 13 shows a two-shaft installation similar to that shown in Fig. 12 with the difference that instead of the turbines operating the adjacent propeller shafts through alternative gearing they operate the adjacent propeller shafts through additional gearing which results in.a double reduction.

Fig. 14 illustrates diagrammatically the form of clutch which may be employed at the position 51 in Fig. 13.

Fig. 15 shows a three-shaft installation in which at full power each shaft is driven by a, high pressure and a low pressure turbine operating through single reduction gearing while at low powers the high pressure and low pressure turbine on the center operative and the shaft are disconnected, the center shaft being then driven by a cruising turbine the exhaust from which passes to the high pressure turbine on one wing shaft and thence to the low pressure turbine on the other wing shaft, the remaining high pressure and low pressure turbines being rendered 1nfull power gear wheels on the wing shafts are disconnected from their propeller shafts and connected to the pinions of the low power gearing and the low power gear Wheel connected to the center propeller shaft, whereby the wlng shafts are idle at low powers while the center shaft is driven by a cruising turbine through single reduction gearing and by one high pressure and one low pressure turbine through double reduction gearing.

Fig. 16 shows a three-shaft installation somewhatsimilar to that shown in Fig. 15 with the difference that no full power turbines are provided upon the center shaft, the arrangement being such that at full power each wing shaft is driven by a high pressure and a low pressure turbine operating through single reduction gearing, while the center shaft is driven by a cruising turbine also operating through single reduction gearing; while at full power the cruising turbine is not working with maximum efficiency it develops sufficient power to prevent the propeller dragging. At low powers the connections and steam flows are similar to those employed in Fig. 15. g

In carrying the present invention into efiect according to one form and as applied to a two-shaft installation employing turbines (see Fig. 1) there are provided high pressure and low pressure turbines 1 and 2 respectively. The high pressure turbine 1 at high powers is clutched directly to the shaft or. while the low pressure turbine 2 at high powers is clutched directly to the other shaft 5. Under these conditions steam is admitted by the conduit 3 to the high pressure turbine from which it passes by the conduit 4 to the low pressure turbine 2 and both shafts a and b are driven directly.

Upon the shaft a of the high pressure tur bine there are provided a gear wheel 5 at the astern end and a pinion 6 at the forward end. Suitable clutch devices 7 and 8 are provided by which respectively the wheel 5 can be clutched to and the rotor of the high pressure turbine declutched from the shaft a or vice versa while the pinion 6 can be clutched to or declutched from the rotor of sure turbine which engages with the pinion 6 at the forward end of the high pressure turbine. Clutch means 11 are provided by which the wheel 10 can be clutched to and the rotor of the low pressure turbine 2, declutched from the propeller shaft 6 or vice versa. Clutch means 12 are also provided by which the pinion 9 can be clutched to or disconnected from the rotor of the low pressure turbine 2.

Under cruising conditions the gear wheel 5 is clutched to the propeller shaft a and the high pressure rotor declutched from the propeller shaft or and clutched to the high pressure pinion 6. The gear wheel 10 is clutched to the propeller shaft band the low pressure rotor is declutched from the shaft 12 and clutched to the pinion 9. Steam is admitted to the high pressure turbine 1 from which it I As an alternativeto the arrangement dc scribed a cruising stage 13 may be provided in the high pressure turbine 1 in which case at low powers the turbine 1 may be fed with steam through the conduit 14.

Again, as an alternative a cruising turbine 15 may be provided (see Fig. 2) connected by gearing to the high pressure or low pressure gear wheel and exhaustingby the con-' "duit 16 in series through the high pressure and low pressure turbines 1 and 2. In Fig.

2 the pinion 17 of the turbine 15 is shown engaging the gear wheel 10', and clutch means 18 are provided to disengage the turbine 15.

According to a modified construction applied to a two-shaft installation (see Fig. 3), a high pressure turbine 1 is provided upon one propeller shaft a and a low pressure turbine 2 upon the other shaft 6. At the astern end of the low pressure turbine a pinion 9 is provided upon the propeller shaft 7) with clutch means 12 by which it can be connected when desired to the rotor of the low pressure turbine 2. At the astern end of the high pressure turbine a gear wheel 5 is provided meshing with the pinion 9 upon the low pressure shaft. Clutch means 7 are provided by which the rotor of the high pressure turbine 1 can be connected to the propeller shaft a and the gear wheel 5 disconnected from the shaft, or vice versa. A second gear wheel 19 is provided upon the rop'eller shaft Z) with which the pinion 1 of a cruising turbine 15 engages. means 20 are provided whereby this second wheel 19 may be connected to the propeller shaft 6 when required. Under full power conditions the last-named clutch 20 is open Clutch and the rotors of the low and high pressure turbines 1 and 2 connected to their respective propeller shafts a and 5. Steam is admitted to the high pressure turbine from which it passes to the low pressure turbine. The two propeller shafts are thus directly driven under full power conditions. At low owers the rotor of the high pressure turblne 2 is disconnected from its propeller shaft 6 and remains stationary, while the gear wheel 19 upon the low pressure propeller shaft 5 is clutched to that shaft. v The low pressure rotor is clutched to th pinion 9 which runs loose on the propeller shaft 6, while the gear wheel 5 upon the propeller shaft a is clutched to that shaft. Steam is admitted to the cruising turbine 15 from whence it passes to the low pressure turbine 2.

Under these conditions the low pressure turbine 2 drives the propeller. shaft a through gearing 9, 5, while the propeller shaft 2) is also driven by the cruising turbine 15 through gearing 17 and 19.

According to the second modification as applied to a three-shaft installation (see Fig. 4) a high pressure turbine 1 is provided upon the center shaft (1 and low pressure turbines 2 upon the wing shafts Z) and b.

At the astern end of the turbines 2 pinions 9 are provided upon the wing shafts b and b and a gear wheel 5 upon the central shaft (1, the pinions and gear wheel being in mesh. At the forward end of the turbines 2 gear wheels 10 are provided upon the win shafts and a pinion 6 upon the center sha t, these gear wheels and pinion being in mesh.

Clutch means 12 are provided between the pinions 9 upon the wing shafts and the low pressure rotors and upon the center shaft a clutch means 7 such that either the gear wheel 5 or the rotor of the high pressure turbine 1 can be connected to the center shaft a.-

Clutch means 11 are also provided upon the wing shafts such that the win shafts I), b can be connected either to t e gear wheels 10 or to the rotor of'the low pressure turbines 2, and between the pinion 6 on the center shaft a and the rotor of the high pressure turbine 1 clutch means 8 are provided.

Under full power conditions, the rotors of all three turbines are connected directly. to their propeller shafts a, b and b and all the gearing is disconnected and remains stationary. Steam is admitted to the high pressure turbine, the exhaust from which is divided between the low pressure turbines.

Under low power conditions all the rotors are disconnected from their shafts, while the gear wheels 5 and 10 upon the center and wing shafts are connected to those shafts. The pinions 6 and 9 upon the center and win shafts are connected to the rotors of the igh and low pressure turbines respectively. Steam is admitted as before to the high pressure turbine, from which it passes to the low pressure turbines.

Under these conditions the high pressure turbine drives through its pinion 6 and the gear wheels 10 the two wing shafts b and 5 while the two wing turbines 2 through their pinions 9 and the gear wheel 5 drive the centershaft a.

As an alternative arrangement, a cruising stage 13 may be provided in the high pressure turbine.

As a further alternative arrangement, (see Fig. 5) a cruising turbine, 15 may be provlded, connected by a pinion 17 and clutch 18 to the pinion 6 upon the center shaft (1.

According to a third modification, as applied to a two-shaft installation (see Figs. '610) pairs of turbines are provided, one pair for each propeller shaft.

The turbines 1 and 2 of each pair are arranged on either side of an extension a and 6" of each propeller shaft. One of these extensions b" carries at its foremost end a gear wheel 10, while the other a" carries a pinion 6 meshing with the gear wheel 10.

The extensions are provided at their astern ends with claw couplings 34 and 21, provided with claws 35 and 66 respectively, and the forward ends of the propeller shafts are also provided with claw couplings 22 and 23.

Upon each of the extension shafts at the astern end, two gear wheels 5, 24 and 9, 25 are provided, the gear members 5 and 9 being in engagement. The other gear members, viz., 24 and 25 are en aged by the pinions 26 of the pairs of tur ines.

The gear wheels 24, 25, 5 and 9 respectively are provided with claw couplings 27, 28, 29 and 30, these claw couplings being preferably so positioned that they lie ad jacent to the claw couplings 22 and 23 on the forward ends of the propeller shafts.

The couplings upon one of the shafts b" are so arranged that under full power conditions the larger gear wheel 25 of that pair can be connected directly to its propeller shaft 5 (see Fig. 7), the gear wheel 9 and the extension shaft 12 being allowed to run free. The connection is made by moving a toothed sleeve 31 so that its teeth 64 and 65 engage the claws 23 and 28 respectively. By this means, the pair of turbines 1-, 2 belonging to that propeller shaft, viz., shaft I) operate it through single reduction gearing 26, 25.

The clutches of the other shaft a" are so arranged that under full power conditions, the gear wheel 24: is connected to its propeller shaft a, while the gear wheel 5 and the extension shaft a" of the propeller shaft are free (see Fig. 8).

This connection is made by moving a. toothed sleeve 36 so that its teeth and 71 engage the claws 22 and 27 respectively.

Under cruising conditions the clutches of the gear wheels 9 and 25, are arranged so that the'extension shaft 6" iscoupled to its 1 co-axial propeller shaft 6, while the two gear 1 while the sleeve 31 is'moved into such a position that its teeth 64 and 65 engage with wheels 9 and 25 are coupled so as to-rotate as one. This is effected by means of a toothed sleeve 32 adapted to slide on the boss of the wheel 25 to which it is connected by keys or equivalent device, the teeth 33 ,of the sleeve 32 engaging the teeth 30 on' the wheel 9,

the claws 23 and 66 respectively (see Fig. 9).

The clutches of theothergear wheels 5' and 24' are operated so as to connect the ex tension shaft 00" with the wheel 24 by means of a. member 34 sliding on the keys of the shaft a"? and having teeth 35 which engage 1, 2 which at full power drive the propeller the teeth 27 on the boss of the wheel 24, while the wheel 5 is coupled to its propeller shaft 0;. This is done by a sleeve 36 sliding on the claws 22 and having teeth"- 37 engaging the teeth 29 on the boss of the wheel 5 (seeFig. 10).

By these connectlons the pair of turbines shaft a through single reduction gearing 24, 26, operates the other propeller shaft 6 at low power conditions, through double reduction gearing, the power passing from the pinions, 26 of the turbines to their gear wheels 24, thence through the extension shaft a clutched to this gear wheel, to the pinion 6 at the forward end of this extension shaft, and so through the gear wheel 10 of the other extension shaft b to the other propeller shaft 6.

At the same time, under low power con ditions, the pinions 26 of the other pair of turbines, 1, 2, transmit their power to their gear wheel 25, from which the power passes to the adjacent pinion 9 coupled to that wheel, and thence to the gear wheel 5 which is mounted upon the other extension shaft a and is coupled'directly to the other propeller shaft a.

According to a fourth modification (see Fig. 11) a pair of shafts a and 6 in a fourshaft installation are provided with turbines similar to those shown in. Fig. 1, while the other pair of shafts a. I and b" are provided with turbines and gearing similar to those shown in Fig. 3. At full power each of the high and low pressure turbines drives its coaxial propeller shaft directly, the cruising turbine 15 being disconnected from its pinion 17 by a clutch 18 and the gear wheel 19 being disconnected from the propeller shaft b". I

At low powers the gear wheel 19 is connected to the propeller shaft 6 by the clutch 20 and the cruising turbine 15 is connected to its inion 17 by the clutch 18 and thus drives t e propeller shaft 6 through the gearing 17 and 19. The exhaust from the cruising turbine passes to the high pressure turbine 1 upon the propeller shaft a from whence it divides and passes to the low pressure turbines, 2, 2, situated upon the shafts b and b". I

At low powers the clutches of the tur . bines 1, 2 upon the shafts a andb are so mampulated that the high pressure turbine drives the propeller shaft 6 through the gearlng 6, 10 while the low pressure turbine drives the propeller shaft a through the gearlng 9, 5, Similarly at low powers the turbine 1 upon the propeller shaft a is disconnected from and the gear wheel 5 is connected to the propeller shaft a." and the low pressureturbine 2 upon the shaft 5 is connected to the pinion 9 and disconnected from the propeller shaft 1)", so that the turbine 2'drives the the gearing 9, 5. I

According to a fifth modification shown in Fig. 12, high and low pressure turbines 111, 222 and 1, 2 are provided upon the propeller shafts .a and b respectively. These turbines are connected by pinions 26 with gear wheels 24 upon the propeller shafts a and b. Thereare also provided upon each of the propeller shafts gear wheels 40 with which engage pinions 41 mounted upon extensions of the pinion shafts of the high pressure and low pressure turbines 111 and 2. -.Su1table clutches 42 are provided so arranged that either the gear wheels 24 or the gear wheels 40 can be connected'to the propeller shafts a and 6. Further clutches 43 are provided between the pinions 26 and 41 so arranged that the -high pressure turbine 111 and the low pressure turbine 2 can be connected either to their pinions 26 or to the pinions 41. Furtherclutches 44 are provided so arranged that the high pressure turbine 1 and the low pressure turbine 222 can be disconnected from their pinions 26 at its pinion 26 and the rotor of the low pres sure turbine'222 to its pinion 26.

Steam is admitted to each high pressure turbine and passes from each high pressure turbine to the low pressure turbine on the same propeller shaft. Each propeller shaft is thus driven at full power by a high pressure turbine in series with a low pressure turbine both turbines operating through single reduction gearing.

At low power the clutches 42 are manipupropeller shaft a" through lated so as to disconnect the gear wheels 24 from the ro eller shafts and to connect the gear w hee s 40 to the propeller shafts. The clutches 43 are manipulated to connect the rotor of the hi h pressure turbine 111 to its pinion 41 and isconnect it from its pinion 26 and to connect the rotor of the low pressure turbine 2 to its pinion 41 and disconnect it from its pinion 26. The clutches 44 are manipulated to disconnect the rotor of the high pressure turbine 1 from its pinshown in Fig. 13, each of the propeller shafts a and b are connected with high andv low pressure turbines which are connected by the pinions 26 andgear wheels 24 wlth the shafts a and b.

Upon an extension of the shaft a. there is provided a pinion'45 and a gear wheel 46. Upon the propeller shaft. 6 there is provided a gear wheel 47 and upon an extension of the shaft 5 there is provlded a pinion 48. A clutch device 49 is provided by which the gear wheel 24 may be connected to the shaft a or to the pinion 45. Clutch means 50 are provided so arranged'as to disconnect or connect the gear wheel 46 and the shaft a. Further clutch means 51, which may be of the form shown in Fig. 14, are provided so'arranged that the gear wheel 47 can be connected to or disconnected from the shaft 5 and the pinion 48 connected to or disconnected from the shaft 54 of the wheel 24. v This is effected by the following means-:-When it is desired to secure the gear wheel 47 to the shaft 5 the portion 52 of the clutch is moved into engagement with the part 55 which is connected to the wheel 47. When it is desired to secure the pinion 42 to the shaft 54 the portion 53 of the clutch is engaged with the portion 56 which is connected to the pinion 48.

When it is desired to connect the shaft 5 directly with the shaft 54 the portions 52 and 53 are engaged with one another, thus leavinglthe wheel 47 and the pinion 48 free.

upon t e shafts b and 54 respectively.

At full power the parts 52 and 53 of the clutch 51 are engaged, thus connecting the wheel 24 with the propeller shaft 5. The clutch 49 is manipulated to connect the wheel 24 with the shaft a and the clutches 44 are manipulated to connect the rotors of Also the clutch 50 is operated to disconnect the wheel 46 from'the propeller shaft a. Steam is admitted to each high pressure turbine and passes to the lowpressure turbine on the same propeller shaft.

It is preferable to admit steam to the turbine 111 by the conduit 3 by passing the cruising stage 13. The shafts a and b are thus driven by the turbines through single reduction gearing at full power.

' At low power the portions 52 and 53 of the clutch 51 are drawn apart-and moved to engage the propeller shaft 5 with the wheel 47 and the shaft 54 with the pinion 48. The clutch 49 is operated to connectv the gear wheel 24 with the pinion 45 and disconnect the wheel 24 from the propeller shaft a. The clutch 50 is manipulated to connect the gear wheel 46 with the propeller shaft a. The clutches 44 'are operated to disconnect the turbines 1 and 222 from their pinions 26.

Steam is supplied to the high pressure I turbine 111 by the conduit 14 so that the steam passes through the cruising stage 13. The exhaust from the turbine 111 passes to the low pressure turbine 2. The propeller shaft 6 is thus driven by the turbine 111 operating through the gearing 26, 24, 45, 47, and the propeller shaft a is driven by the turbine 2 operating through its gear 26, 24 and the pinion 48 and gear wheel 46.

According to a seventh modification as shown in Fig. 15 a three-shaft installationis provided with a high and low pressure turbine to each shaft, the center shaft being provided in addition with a cruising turbine 15. Upon each of the propeller shafts is provided a gearwheel 24 with which engage the pinions 26 of the high and low pressure turbines. In the case of the center shaft the wheel 24 is also engaged by the pinion 17 of the cruising turbine and in this case the wheel 24 is permanently secured to the shaft a. The center shaft a also carries a gear wheel 57 freely mounted upon it which is engaged by pinions 58 freely mounted on the wing propeller shafts b and b. Clutches 44 are provided between the high pressure turbine 1 of the shaft 5 and the low pressure turbine 2 of the shaft 5 and their respective pinions and also between the turbines 111 and 222 and their pinions 26.

Clutches 60 are provided by means of which the gear wheels 24 on the wing shafts can be connected with the wing shafts or disconnected from these shafts and connected to the pinions 58.

Under full power conditions the clutch 18 is operated to disconnect the cruising turbine 15 from its pinion 17 and the clutches 44 are operated to connect the rotors of the ' turbines 1, 2, 111, 222, to their respective pinions 26. The clutch 59 is operated to disconnect the wheel 57 from the shaft a and the clutches 60 are operated to disconnect the pinions 58 from the propeller shafts b and b and to connect the gear wheels 24 with the propeller shafts b and 6'.

Steam is admitted to each high pressure turbine and passes to the low pressure turbine on the same propeller shaft. The propeller shafts are thus all driven through single reduction gears by a high and a low pressure turbine 1n series.

Under low power conditions the clutch 18 is operated to connect the turbine 15 to its pinion 17 and'the clutches 44 are manipulated to disconnect the turbines 1, 2, 111, 222,

' from their pinions 26. The clutch 59 is operated to connect the gear wheel 57 with the shaft a and the clutches 60 are operated to disconnect the gear wheels 24 from the wing shafts and to connect them to the pinions 58.

Steam is admitted to the cruising turbine from which it passes to the high pressure turbine 1 which at full power drives the shaft b and passes thence to the low pressure turbine 2 which at full power drives the propeller shaft 6.

It will be seen that under low power conditions the wing shafts are idle while thecenter shaft is driven by the cruising turbine 15 operating through single reductlon gearing 17 24, and by one high pressure and one low pressure turbine, both operating through double reduction gearing, 26, 24, 58, 57.

As an alternative the turbines and full.

power gearing on the wing shafts can be rendered inoperative at low powers while the cruising turbine and center shaft turbines drive the wing shafts through double reduction gearing. For this purpose a pinion coupled at low powers to the Wheel 24 is provided upon the center shaft in the place of wheel 57 and engages gear wheels upon the wing shafts which take the place of the pinions 58.

According to an eighth modification as shown in Fig. 16, a three-shaft installation is provided with a high and a low pressure turbine for each of the wing shafts, the turbines being connected by pinions 26 with gear wheels 24 mounted on the propeller shafts.

The center propeller shaft a carries a gearwheel 57 which is engaged by pinions 58 freely mounted on the wing shafts. The cruising turbine 15 is provided with a pinion 17 which engages the gear wheel 57.

Clutches 60 are provided by means of which the gear wheels 24 can be connected with the wing shafts or disconnected from the wing shafts and connected to the pinions 58.

At full power the clutches 60 are operated to connect the wheels 24 to the wing shafts and the clutches 44 are operated to connect the and low pressure turbines to their respective pinions.

Steam is admitted to both high pressure turbines and to the cruising turbine. The

exhaust from each high pressure turbine.

passes to its associated low ressure turbine. The exhaust from the cruising turbine is d vided between the two high pre'ssureflturmes.

As at full power the cruisin turbine is not working with maximum e ciency it is arranged to exhaust to such a stage of the h gh pressure turbine that it will have only a small pressure drop and therefore develop a small power, but sufficient to insure that the center propeller -'does not drag.

Atlow powers the clutches 44 are operated to disconnect the high pressure turbine and the low pressure turbine. The clutches 60 are operated to disconnect the wheels 24 from the shafts b and b and to connect the wheels 24 to the pinions 58. Under these conditions steam is fed to the cruising turbine which exhausts to that high pressure turbine which remains connected to its pinion and the exhaust from this high pressure turbine is taken to the low pressure turbine which remains connected to its pinionj Under these conditions-the wing shafts are idle In all the forms described it will be seen that the desired objects are attained in a simple manner with a minimum number of wheels, use being made of the opposite direction of rotation of adjacent propeller shafts.

It will be understood that although the invention has been described with reference to turblnes, it is equally applicable to instal-- lations in which the place of turbines as the driving motors employed is taken by electric motors, hydraulic transformers, reciprocating engines, or any other suitable motor.

It will further be understood that when turbines are employed they may be of the reaction or impulse type, or of combinations of these types. They may be provided with cruising stages and cross-connected in an suitable manner.

Astern'turbines may also be provided to operate any of the propeller shafts.

The clutches employed may be of the claw,

friction, electrical or any suitable type and may be provided with operating mechanism by which means the various clutches can be operated simultaneously when changing from one power to another.

Interlocking mechanism may also be provided between the clutch operating mechanism and the steam supply valves of the turbines, arranged to prevent the steam supply valves being opened until the clutches are in the correct working position corresponding to the use of such steam connections. Such interlocking mechanism is described, for example, in the specification of British Letters Patent No. 804: of 1913.

Many modifications within-the scope of the appended claims may be made in the carrying out of the invention without departing from the spirit of the same.

Claims:

1. A ship propulsion installation comprising a motor, a propeller adapted to be driven by the motor at low powers, and another propeller adapted to be driven by the motor at full power, the ratio of the revolutions of the motor to the revolutions of the propeller it drives differing at low powers from the ratio at full power.

2. A ship propulsion installation c0mpris ing a main driving shaft, a propeller shaft operated by the main shaft at full power, and another propeller shaft operated by the main shaft, the ratio of the revolutions of the main driving shaft to the revolutions of the propeller shaft it drives differing at low powers from the ratio at full power.

3. A ship propulsion installation comprising a steam turbine, a propeller adapted to be driven by said turbine at low powers, another propeller adapted to be driven by said turbine at full power, the ratio of revolutions of the turbine to the revolutions of the propeller it drives differing at low powers from the ratio at full power.

4. A ship propulsion installation comprising in combination a high pressure turbine, a low pressure turbine, a propeller adapted to be driven by said turbines at low powers, and another propeller adapted to be driven by said turbines at full power, the ratio of revolutions of the turbines to the revolutions of the propeller differing at low powers from the ratio at full power.

5. A ship propulsion installation comprising in combination two turbines, a pair of propellers each adapted to be driven by one of said turbines at low oWers, and adapted to be driven by the otier of said turbines at full ower, the ratio of revolutions of each tur ine to the revolutions of the propeller it drives differing at low powers from the ratio at full power.

6. A ship propulsion installation comprising in combination two propeller shafts, extensions of said propeller shafts, two gear wheels of different diameters mounted on said extensions in proximity to the end of the propeller shaft, gear wheels at the forward end of said extensions, said gear wheels inter-engaging in pairs, a pair of turbines, pinions rotating with said turbines, one of said pinions engaging with a gear wheel on one of said extensions, the other pinion engaging with a gear wheel on the other of said extensions, and clutching means between each of said turbines and each of said propeller shafts so arranged that each turbine at low powers drives a different propeller from that which it drives at full power, the ratio of the revolutions of the turbine to the revolutions of the propeller it drives differing at low powers from the ratio at full power, as set forth.

7. A ship propulsion installation comprising in combination two propeller shafts, extensions of said propeller shafts, two gear wheels of different diameters mounted on said extensions in proximity to the end of the propeller shaft, gear wheels at the forward end of said extensions, said gear wheels inter-engaging in pairs, a pair of turbines each including a high pressure turbine and a low pressure turbine, pinions rotating with said turbines, one of said pinions engaging with a gear wheel on one of said extensions, the other pinion engaging with a gear wheel on the other of said extensions, and clutch ing means between each of said turbines and each of said propeller shafts so arran ed that each turbine at low powers drives a different propeller from that which it drives at pull power, the ratio of the revolutions of the turbine to the revolutions of the propeller it drives differing at low powers from the ratio at full power, as set forth.

In testimony whereof, we have affixed our signatures.

CHARLES ALGERNON PARSONS. ROBERT JOHN WALKER. STANLEY SMITH COOK.

LOUIS MORTIMER DOUGLAS.

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