Engine crankshaft indexing method and tool
BACKGROUND AND SUMMARY 
     The invention relates to rotational indexing of a crankshaft in an internal combustion engine to facilitate test and repair adjustments requiring precise indexing of rotational degrees of the crankshaft. 
     The invention particularly arose from a need to provide precise indexing on marine diesel engines subject to heavy usage, which requires frequent and periodic valve clearance adjustment. Diesel engines raise the particular problem of a high compression ratio pressure head to be overcome in torquing or rotating the engine through precise small scale indexed angular degrees. This problem is further amplified in those applications where the mechanic may wish to not relieve compression pressure in any of the cylinders by removing a glow plug or the like, to avoid the necessity of installing a new gasket and resealing such broken seal. In such applications, the high pressure head which must be overcome in minutely rotationally indexing the crankshaft presents problems as to preciseness and exactness. 
     In previous diesel engines and the like, extended bolts were provided on the crankshaft pulley, and a pry bar was used thereacross to rotate the engine. In another prior method, the starter motor is used to rotate the engine. None of these prior systems satisfies the need to accurately rotate the engine for precise indexing of rotational degrees of the crankshaft to facilitate test and repair adjustments. The present invention addresses and solves this problem in a particularly simple and efficient manner. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Prior Art 
     FIG. 1 shows an exploded perspective view of a portion of an internal combustion engine known in the prior art. 
     FIG. 2 is a sectional view of the structure of FIG. 1. 
     Present Invention 
     FIG. 3 is a perspective view of a tool constructed in accordance with the present invention. 
     FIG. 4 is an end view of the tool of FIG. 3. 
     FIG. 5 is a sectional view like FIG. 2 and shows use of the tool of the present invention. 
     FIG. 6 is a sectional view like FIG. 5 and shows a further embodiment. 
     FIG. 7 is a view taken along line 7--7 of FIG. 6. 
     FIG. 8 is an exploded perspective view showing alternative structure in accordance with the invention. 
     FIG. 9 is an end view like FIG. 4 and shows another embodiment. 
     FIG. 10 is an end view like FIG. 4 and shows another embodiment. 
    
    
     DETAILED DESCRIPTION 
     Prior Art 
     FIGS. 1 and 2 show an internal combustion engine 12 having a crankshaft 14 extending axially from a crankcase 16. An alternator and accessory pulley 18 is mounted to the end of the crankshaft by a nut 20. A vibration damper or harmonic balancer 22, where needed, is mounted to pulley 18 by a plurality of bolts such as 24 and 26, and a flat disc 28 is mounted to pulley 18 by the same bolts, with harmonic balancer 22 between disc 28 and pulley 18. The plurality of bolts such as 24 and 26 extend around an inner periphery of harmonic balancer 22 and pulley 18, radially outward of the axis 30 of rotation of crankshaft 14. Disc 28 extends radially from axis 30 and has a plurality of openings such as 32 and 34 receiving respective bolts. The bolts have enlarged heads, e.g. at 36 and 38. Openings such as 32 have a diameter larger than the diameter of the respective bolt head, such as 36, and slides thereover upon attachment of disc 28. Opening such as 34 have a diameter smaller than the respective bolt head such as 38, such that bolt 26 extends through opening 34 and through harmonic balancer 22 into pulley 18 and mounts disc 28 to pulley 18 by engagement of bolt head 38 against the right face of disc 28. 
     In engines with power steering, power steering pulley 40 is mounted to disc 28 by a plurality of bolts such as 42 extending around an inner periphery radially inward of bolts 24, 26. Pulley 40 has a central axial opening 44 therein. 
     During test and repair adjustments requiring crankshaft rotation in such prior engines, it is known to provide elongated bolts into pulley 40 or 18, and to use a pry bar to rotate the crankshaft. Another method is to use the starter motor to rotate the crankshaft. 
     Present Invention 
     FIGS. 3-10 illustrate the present invention and use like reference numerals from FIGS. 1 and 2 where appropriate to facilitate clarity. 
     FIGS. 3 and 4 show an engine crankshaft rotation tool 50 comprising a disc 52 removably attachable to pulley 18, with or without harmonic balancer 22, and having a shank 54 extending axially from tool disc 52 on the opposite side 56 of the disc from the crankshaft side 58, and axially colinear with crankshaft 14. Shank 54 is grippable for rotating such shank. For example, shank 54 has a hex, square or other configuration grippable by a socket such as 60, FIG. 5, for rotation by a breaker bar or ratchet such as 62. Rotation of shank 54 rotates disc 52 which engages at its openings such as 64 and 66 respective bolts such as 24 and 26 at respective bolt heads 36 and 38 and imparts rotation to pulley 18 and crankshaft 14. 
     In the repair procedure, the plurality of bolts 42 are removed, followed by removal of pulley 40, followed by removal of bolts such as 26, followed by removal of disc 28. Tool 50 is then applied such that openings such as 64 around its periphery engage respective bolts at heads such as 36 to enable the noted impartation of rotation for the noted indexing of rotational degrees of crankshaft 14. In diesel engines, it is particularly desirable to remove bolts such as 26 prior to application and engagement of tool 50, and then reinsert bolts such as 26 back through openings or holes such as 66 in tool disc 52 to attach the tool to pulley 18 and prevent slippage there-off during rotational indexing of crankshaft 14 against the high torque high compression pressure of a diesel engine, without removing the compression-relieving seals such as at glow plugs or the like. This is attractive to mechanics at a time saving and quality improving measure. 
     After rotational indexing, bolts such as 26 are removed, followed by removal of tool 50, followed by reinstallation of disc 28 and bolts such as 26, followed by reinstallation of pulley 40 and bolts such as 42. 
     In the embodiment shown in FIGS. 3-5, tool 50 is a one-piece member wherein shank 54 is welded to or otherwise integrally connected to disc 52. In this embodiment, an alternative to that above described is to replace disc 28 by disc 52 which remains permanently installed in the engine, with shank 54 extending axially from disc face 56 through axial opening 44 of pulley 40 and remaining therein during the final assembled condition of the engine, without removal of other parts otherwise necessary for rotational indexing of the crankshaft during test and repair adjustment. In FIGS. 6 and 7, square shank 54a is integrally welded to disc 52. Shank 54a and disc 52 remain in place after assembly of the engine, and after the noted test and repair adjustments involving rotational indexing of the crankshaft. The end 68 of shank 54a extends rightwardly beyond pulley 40 for gripping by a socket 60, wrench, or the like, to rotate shank 54a to facilitate the noted test and repair adjustments requiring precise indexing of rotational degrees of crankshaft 14. 
     In FIG. 8, disc 70, corresponding to disc 52, has a central configured or keyed opening 72 axially colinear with crankshaft 14 and receiving in keyed relation a shank 74, such as an extension for a socket or ratchet wrench, or the like. Disc 70 includes openings 64a and 66a comparable to openings 64 and 66 in FIGS. 3 and 4. In the embodiment in FIG. 8, disc 70 replaces disc 28 in FIG. 1 and remains installed as part of the engine. Upon test and repair adjustments requiring precise indexing of rotational degrees of crankshaft 14, shank 74 is inserted through opening 44 of pulley 40 into configured opening 72 in keyed relation therewith. During test and repair adjustment, rotation of shank 74 inparts rotation to disc 70 which rotates pulley 18 which rotates crankshaft 14. After indexing rotation, shank 74 is removed from opening 72 of disc 70 through opening 44 of pulley 40. 
     FIG. 9 shows an alternate embodiment involving five enlarged openings or slots 64 of a diameter larger than the diameter of the respective bolt heads such as 36, 38, to slide thereover during attachment of the tool disc to pulley 18. The remaining opening 66 has a diameter smaller than respective bolt head 38 such that the tool disc is held on pulley 18 by bolt 26 where desired in hard turning applications, such as diesel engines. FIG. 10 shows another alternate embodiment wherein all of the openings 64 have a diameter larger than the respective bolt heads. 
     It is recognized that various equivalents, alternatives and modifications are possible within the scope of the appended claims.