Power tester for outboard drive assemblies
BACKGROUND OF THE INVENTION 
     Various forms of dynamometers and other structures for applying variable loads to engine drive assemblies have been heretofore designed. In addition, some of these previously known assemblies have been specifically designed for use in conjunction with outboard motors and inboard/outboard drive assemblies for simulating over the water operation to enable outboard motors and inboard/outboard drive assemblies to be tested without actually operating the associated boat on the surface of the body of water. 
     Examples of previously patented assemblies or structures of this type are disclosed in U.S. Pat. Nos. 2,218,463, 2,669,870, 2,831,345, 2,982,128, 2,993,369, 3,505,863 and 3,592,053. 
     SUMMARY OF THE INVENTION 
     The power tester of the instant invention is in the form of a hydraulic motor supported from the lower unit of an outboard motor or inboard/outboard drive assembly with the propeller shaft (after the propeller has been removed therefrom) drivingly coupled to the rotary input shaft of the hydraulic motor. Bracing is provided for stationarily supporting the motor from the associated lower unit and the hydraulic motor is serially connected in a closed loop hydraulic circuit equipped with a throttle valve whereby variable loads may be placed upon the propeller shaft of the unit for testing purposes. 
     The main object of this invention is to provide a variable load developing unit for the propeller shaft of an outboard motor or inboard/outboard drive assembly. 
     Another object of this invention is to provide an apparatus whereby a variable load under varying operating speed conditions may be placed upon an associated propeller shaft. 
     Still another object of this invention is to provide a power tester in accordance with the preceding objects and which may be submerged within a test tank or utilized in conjunction with a conventional flushing attachment for an outdrive assembly. 
     A final object of this invention to be specifically enumerated herein is to provide an apparatus in accordance with the preceding objects and which will conform to conventional forms of manufacture, be of simple construction and easy to use so as to provide a device that will be economically feasible, long lasting and relatively trouble free in operation. 
     These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of the lower unit of an outboard motor with the power tester of the instant invention operatively associated therewith; 
     FIG. 2 is a fragmentary elevational view of the hydraulic circuitry of the power tester including the hydraulic motor thereof, portions of the hydraulic circuit being broken away; 
     FIG. 3 is a fragmentary side elevational view of the power tester in operative association with the lower unit of an inboard/outboard drive assembly disposed within a test tank; 
     FIG. 4 is a top plan view of the lower unit mounted portion of the power tester in operative association with the propeller shaft of an associated lower unit; 
     FIG. 5 is a fragmentary vertical sectional view taken substantially upon the plane indicated by the section line 5--5 of FIG. 4; 
     FIG. 6 is a rear elevational view of the assemblage illustrated in FIGS. 4 and 5 and with the hydraulic motor removed; and 
     FIG. 7 is a front elevational view of the assemblage illustrated in FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now more specifically to the drawings, the numeral 10 generally designates the upstanding power leg of a conventional outboard motor including a lower unit 12 provided with a front-to-rear extending horizontally elongated gear housing 14 from whose rear end a propeller shaft 16 extends (the marine propeller usually mounted thereon having been removed therefrom). 
     From FIG. 5 of the drawings it may be seen that the lower unit 12 includes a side water intake 18 and from FIG. 1 of the drawings it may be seen that the lower unit 12 may have a conventional flushing attachment referred to in general by the reference numeral 20 operably clamped thereabout over the intake 18 in order to supply sufficient cooling water to the outboard motor 10. 
     The propeller shaft 16 is splined as at 24 and the splined rotary input shaft 26 of a hydraulic motor 28 including an outlet 30 and an inlet 32 is coupled to the propeller shaft 16 by means of a sleeve coupling 34 which is internally splined. 
     A mounting assembly referred to in general by the reference numeral 36 is provided and includes a main channel-shaped plate 38 consisting of an upstanding bight portion 40 and a pair of upstanding rearwardly directed opposite side flanges 42 and 44. The bight portion 40 has a central bore 46 formed therethrough and a plurality of smaller bores 48 spaced thereabout. The rotary input shaft 26 of the hydraulic pump 28 extends through the central bore 46 and the forward end of the hydraulic motor 28 is supported from the bight portion 40 by means of fasteners 50 secured through the bores 48 and threadedly engaged in the motor 28. 
     The opposite side flanges 42 and 44 include oppositely outwardly projecting threaded studs 52 and 54 to which the lower ends of a pair of upstanding arms 56 and 58 are secured by means of fasteners 60 threadedly engaged with the studs 52 and 54. The arms 56 and 58 include a plurality of bores 62 formed therein at points spaced therealong through which the studs 52 and 54 are receivable. Accordingly, the effective height of the arms 56 and 58 relative to the channel member 38 may be adjusted. The upper ends of the arms 56 and 58 include padded inwardly directed flanges 60 and 62 which lap over opposite side portions of a horizontally outstanding peripheral cavitation plate 64 carried by the lower unit 12. 
     In addition to the arms 56 and 58, the rear ends of a pair of front-to-rear extending clamp arms 66 and 68 are also secured over the studs 52 by means of the fasteners 60. The forward ends of the arms 66 and 68 curve toward each other in front of the forward end of the gear housing 14 and are clamped together by means of a clamping bolt 70. In this manner, the hydraulic motor 28 is securely removably supported from the lower unit 12. 
     With attention now invited more specifically to FIG. 3 of the drawings, it may be seen that the hydraulic motor 28 may also be supported in operative association from the lower unit 72 of an inboard/outboard drive assembly supported from a boat hull 74. If it is desired, the hydraulic motor 28 and the lower unit of the assembly 72 may be submerged within a conventional test tank 76. In this case, it is not necessary to utilize a flushing attachment such as the attachment 20 in conjunction with the lower unit 72. 
     With attention now invited more specifically to FIG. 2 of the drawings, it may be seen that the outlet 30 and inlet 32 of the pump 28 are serially connected in a closed loop hydraulic circuit 78 and that the circuit 78 includes a throttle valve 80 serially connected therein and provided with an adjustment operator 82. In addition, the circuit 78 includes a bypass line 84 which bypasses the throttle or control valve 80 and the inlet end of the bypass line 84 has a pressure relief valve 86 operatively associated therewith. Further, a pressure gauge 88 is communicated with the circuit 78 intermediate the pump outlet 30 and the pressure relief valve 86. 
     The components 80, 82, 84, 86 and 88 may be supported from a suitable cabinet 90 which also supports a tachometer 92 and tachometer selector switch 94 for adapting the tachometer 92 to be utilized in conjunction with marine engines having different numbers of cylinders. Still further, the cabinet 90 may include a heat indicator 96 for operative association with the power head of the marine drive unit being tested. 
     In operation, the hydraulic pump 28 is mounted in operative association with the propeller shaft of the marine drive assembly to be tested and suitable means such as the flushing attachment 20 or test tank 76 may be utilized to ensure that the power head of the marine drive unit will be supplied with sufficient amounts of cooling water. Then, the marine drive unit may be operated and varying loads may be placed upon the propeller shaft thereof by the control valve 80. The operating speed of the marine drive unit may be monitored by the tachometer 92 and the operation of the power head portion of the associated marine drive unit may be carefully monitored by various testing equipment (not shown) while the marine drive unit is operating under a load as a result of the variable throttling of the closed loop hydraulic circuit 78. 
     The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.