Abstract: An apparatus and method are disclosed which ensures that a rotor-shaft assembly is in rotational balance after assembly of the individually balanced components by preventing the creation of any imbalance during assembly. The rotor member is formed with an annular groove about the nose portion at a point near its mounting face, which during assembly is crimped before any shaft bending occurs, thereby eliminating any rotor-shaft imbalance.

Abstract: A composite, carbon-carbon rotor or rotor hub (20) for use in power translating devices, such as in a turbine engine or in fluid pumps, includes a plurality of carbon-carbon laminate plies (P1-P25) layered to form the thickness of the rotor. The plies include alternating plies of cloth and spiral plies of fibrous material having different diameters to provide a desired variation in the cross-sectional configuration of the rotor. The individual spiral plies may vary in thickness from near the center to the outer edge and may be either tapered or formed to other contours. The cloth plies are positioned at predetermined orientations such that the strand axes are not aligned. These plies consist of fibrous carbon or graphite filament tape preimpregnated with a thermosetting polymer material, such as phenolic resin.

Abstract: A method for modifying the stator of an automotive torque converter by using an adaptor is discussed. The adapter includes a casting or machined part having a cylindrical portion on a flange for bearing against a surface of the stator. The stator has its lip removed, after which the adapter is coaxially aligned with the stator support shaft and the inner race splined thereto and then fastened to the stator fasteners extending through the flange and into the stator. The modified stator can now accommodate a heavier duty thrust bearing which improves reliability of the torque converter.

Abstract: A gas turbine engine rotor (18) and shaft (28) are secured against radial loosening between the shaft (28) and axially spaced rotor spigots (24, 26) by annular spacer rings (42, 43) which are fabricated from a material having a thermal coefficient of expansion significantly higher or lower than the thermal coefficients of the shaft (28) or rotor (18). The ring (42, 43) is pre-assembled during production of the engine in an interference fit with either the rotor hub (22) or the shaft (28), being sized to remain tight with the pre-assembled member over a range of operating temperatures, and becoming more tightly fit with the other member due to differential thermal expansion therebetween.

Abstract: A turbine disk assembly 20 has an extension including arms 34 and a groove 38. Nut 40 engages the groove and bears against the extension. A square head 48 on the nut fits a standard torque multiplying wrench and arms 34provide a reaction so that no adapter tool is required. Groove 38 permits pulling the disk assembly by use of the nut, and also allows sleeve 50 to hold the nut from loosening.

Abstract: The present invention includes an overhung turbine wheel which is provided with at least one ring of turbine blades and is connected with a shaft. In order to control the thermodynamically required circumferential speeds necessary to achieve maximum efficiency, the turbine wheel is designed as a closed disk which is narrow in the axial direction. The turbine wheel is integral with the turbine blades and furthermore is connected to the shaft through planar connecting surfaces having interfitting teeth. The turbine wheel has a relatively low mass, and the interfitting teeth allow a simple and optimal centering connection. Radial-flow turbines of this kind are standardized in model series, the turbine wheels and shafts in each case being provided with similar interfitting teeth to allow mutual combinations as desired.

Abstract: A turbine rotor with air cooled blades has a turbine disk and a continuous hoop circumferential turbine rim bonded thereto. The rim has a plurality of circumferential rings extending toward the disk and forming circumferential chambers therebetween.Near the outer edge of the turbine rim are transversely extending openings. The rim is wire cut from these openings from the outer periphery forming segmented blade platforms, allowing the thermal expansion of the platform to occur. Tubes within the openings convey cooling air to the circumferential chambers, from which it passes to the blade interiors and through cooling openings in the platforms.

Abstract: Apparatus for cooling and thermally isolating turbocompressor foil bearings. The bearing journal includes a hollow shaft through which gas is positively circulated to cool the shaft. A slinger at one end of the shaft develops a centrifugal pumping action during operation of the turbocompressor by virtue of a plurality of radially directed gas passages. Pressurized gas may be introduced from the compressor into the interior of the hollow shaft and, after traversing the shaft, returned to the compressor. The invention includes arrangements for protecting the bearing against combustion products which may leak past turbine wheel seals by removing such combustion products before they can reach the bearing.

Abstract: A turbine rotor unit and a method of producing the same are disclosed. This turbine rotor unit comprises a ceramic rotor, a ceramic shaft integrally united with the ceramic rotor and a metal shaft provided with a cylindrical portion fixing the ceramic shaft therein and is characterized by having a gap between a substantial portion of the inner peripheral surface of the cylinder portion located near the side of the ceramic rotor and the outer surface of the ceramic shaft. Further, the turbine rotor unit is produced by arranging on one end of the metal shaft a cylindrical portion wherein an inner diameter at its opening side is larger than that at the bottom side, inserting the ceramic shaft into the cylindrical portion, and fixing the ceramic shaft to the cylindrical portion at its small diameter side.

Abstract: A rotor has an inner disk member including a web and a circumferential widened outer portion. A blade member has a continuous circumferential inner edge. At least one of the members has a plurality of axially spaced circumferential rings extending toward the other member. The two members are diffusion bonded together. A stiff lightweight assembly is achieved.

Abstract: A rotor-shaft assembly includes a ceramic solid hubbed turbine rotor having an integral stub shaft interference fit within one end of a generally cylindrically shaped sleeve member. The sleeve member defines a hub portion adapted to mate with a piston ring seal and a coaxial bore therethrough. The interference fit, which is defined by the change in the diameter of the bore, schedules the compressive forces acting on the stub shaft. A metal shaft is brazed within the other end of the sleeve member in a torque transmitting relationship.

Abstract: A metal-ceramic composite fitting assembly is described in which an effective connection between a boss on the ceramic member and the metal shaft member is achieved by providing the shaft with a sleeve formed of a material having a coefficient of thermal elongation comparable to that of the ceramic member, which sleeve is joined to the shaft member and cooperates with a recess therein to engage the boss along its length and to impose thereon compressive gripping forces that increase in magnitude along the length of the boss.

Abstract: A compressor rotor assembly comprises a shaft and at least one disc having integral radially extending aerofoil blades which disc is integral with the shaft. The assembly comprises a matrix material in which a plurality of short reinforcing fibres are so disposed that the majority thereof within the shaft are generally axially aligned while the majority thereof within the aerofoil blades are generally radially aligned. At least one filament wound support ring provides radial support for the aerofoil blades.

Abstract: A cylindrically shaped spacer between a shaft and hub of a turbine rotor of a gas turbine engine as fabricated from a flexible resilient material and interference fitted at discrete points on either side of the transverse axis of the spacer between the shaft and spacer and between the hub and spacer to impart a twist of the spacer about this axis to remain in contact with the hub and shaft throughout its entire rotating envelope.

Abstract: Apparatus for cooling and thermally isolating turbocompressor foil bearings. The bearing journal includes a hollow shaft through which gas is positively circulated to cool the shaft. A slinger at one end of the shaft develops a centrifugal pumping action during operation of the turbocompressor by virtue of a plurality of radially directed gas passages. Pressurized gas may be introduced from the compressor into the interior of the hollow shaft and, after traversing the shaft, returned to the compressor. The invention includes arrangements for protecting the bearing against combustion products which may leak past turbine wheel seals by removing such combustion products before they can reach the bearing.

Abstract: A rotor-shaft assembly which includes a ceramic, solid hubbed turbine rotor having an integral stub shaft brazed within one end of a generally cylindrically shaped sleeve member. A metal shaft is either brazed or cold press fitted within the other end of the sleeve member in a torque transmitting relationship. The stub shaft is formed with an annular relief therearound in order to reduce the compressive forces acting on the stub shaft by the sleeve member.

Abstract: Steam turbine blades are fastened in an outer layer of weld material applied by deposit welding to the outer surface of the rotor body, the composition of the weld material being optimally matched with respect to hot strength and/or corrosion resistance, in particular stress corrosion resistance, to the local mechanical, thermal and chemical requirements. A possible option is additionally to insert a deposit welded intermediate layer of medium alloying element content. Steels with 10-14% Cr, low carbon and additions of Mo and possibly V are preferred as the weld material for the layer.

Abstract: A compressor wheel assembly for turbochargers and the like comprises a compressor wheel including a boreless hub formed integrally as by casting with a circumferential array of aerodynamically contoured centrifugal impeller blades. The wheel hub is secured at its base by inertia welding to a thrust spacer sleeve having an internally threaded bore for threaded reception of a rotatable shaft. In use of the compressor wheel assembly, the absence of a bore within the wheel hub substantially improves wheel fatigue life.

Abstract: A turbocharger for an internal combustion engine, in which the turbocharger has a turbine wheel made in one piece from a ceramic material and having an axially extending support portion which is inserted into a hollow shaft made from a metal material. The support portion of the turbine wheel has, at an end remote from the blade portions, a portion having an increased diameter and tightly fitted to the hollow shaft. An axial first annular slit is formed between the shaft and the support portion. A radial second annular slit is formed between facing surfaces of the shaft and the turbine wheel. These first and second slits are connected to each other and work to alleviate the effects of the different heat expansion coefficients of the metal and ceramic materials on the support portion of the turbine wheel.

Abstract: An improved rotary machine such as centrifugal type compressor adapted to rotate under high load of the type including a plurality of impellers fixedly mounted (shrinkage-fit) on a main shaft. To effectively inhibit the rotor from vibrating due to loosened fitting of the impellers onto the main shaft the improvement consists of each of the impellers being provided with a sleeve portion which is made integral with the impeller. The sleeve portion is located at a position removed from the main part of the impeller along the axial direction of the main shaft with the position being determined in accordance with the theory of strength of materials in such a manner that displacement of the impeller in the radial direction due to centrifugal force resulting from rotation of the rotary machine has no effect on determination of the position of the sleeve portion, wherein the sleeve portion is shrink fit onto the main shaft of the impellers.

Abstract: A metal-ceramic composite article obtained by press fitting a projection of a ceramic member into a hole formed in a metallic member has a high bonding force in the press-fitted portion and is free from separation between the ceramic member and the metallic member. The composite article exhibits high thermal resistance or wear resistance when used as a piston crown in a piston for an adiabatic engine or when used as a cam contacting surface of a tappet.

Abstract: An anti-rotation device for preventing rotation of a wheel with respect to a shaft, wherein the wheel is primarily secured to the shaft by an interference shrink fit, should the interference shrink fit loosen, comprises an annular member separate from yet irrotatably secured to the periphery of the shaft, such as by an interference shrink fit, and a pair of spaced apart restraining tabs coupled to the annular member for receiving a portion of the wheel therebetween. A portion of the radial inner surface of the member may be outwardly tapered toward an axial end to assist dispersion of fluid which may accumulate in the region of the anti-rotation device. The device may include spacing protrusions for axially spacing the device from the wheel and may be disposed between a pair of wheels for preventing undesirable rotation of one or both wheels.

Abstract: A dual alloy radial turbine rotor with high tensile strength hub material exposed in the saddle regions between the blades to prevent fatigue that causes cracks in the saddle regions is manufactured by producing the hub with additional material at the outer portions of a frustoconical rear portion of the hub. After diffusion bonding of the outer surface of the hub to the mating inner surface of the blade rim, portions of the blade rim in the saddle regions are machined away to produce finished saddle configurations with the high tensile strength hub material exposed.

Abstract: A gas turbine including a joint structure is disclosed. According to the joint structure, a ceramic shaft is received in a bore formed in an end portion of a metallic shaft. Brazing filler metal made of Ag-Cu alloy is distributed between the closely fitted surfaces of the ceramic shaft and bore wall, and it extends axially toward the open end of the bore up to a predetermined plane where a ring seal groove formed on the end portion of the metallic shaft lies. The open end of the bore is closed to prevent entrance of exhaust gas into the bore.

Abstract: A rotor for high temperature and high speed applications including a rotatable hub, a plurality of rotor blades mounted on the hub for rotation therewith, and a shroud coupled to the rotor for rotation therewith and lying radially outwardly of at least a portion of the blades so that, upon rotation of the rotor, the shroud is unevenly deformed due to the centrifugal force resulting from the mass of the blades. This uneven deformation of the shroud places it in shear. The shroud is stronger in hoop tension than in shear. Centrifugal members are positioned between adjacent blades to apply a centrifugal force to the shroud between the blades. This causes the shroud to be more evenly deformed to reduce the shear.

Abstract: A hybrid gas turbine rotor having a silicon carbide ceramic turbine wheel portion and a nickel alloy steel shaft portion further includes a hollow silicon carbide ceramic stub shaft integral with the turbine wheel portion having a frustoconical outer surface tapering away from the wheel portion and a tubular end on the shaft portion having an inner frustoconical surface tapering toward the shaft portion at an angle corresponding to the outer surface taper angle. The shaft portion is connected to the wheel portion by shrink fitting the tubular end over the stub shaft so that the shrink fit is the sole medium whereby the wheel portion is supported on the shaft portion and torque is transferred therebetween.

Abstract: Disclosed herein is a metal-ceramic composite body having a ceramic member with a small diameter portion and a large diameter portion which are formed by providing a ceramic member with a projection and a metallic member with a recessed portion or through hole. The ceramic member and the metallic member are bonded together by inserting the small diameter portion into the recessed portion or through hole such that a space being not less than the diameter of the small diameter portion is provided between the edge surface of the metallic member on the side of the ceramic member at the bonding portion and the back surface of the large diameter portion of the ceramic member. The thickness of the edge portion of the metallic member is gradually reduced toward the ceramic member at a radius of curvature of not smaller than 0.4 times as large as the diameter of the small diameter portion. A method of producing the metal-ceramic composite body is also disclosed herein.

Abstract: The disclosure relates to a process for the fabrication of low cost dual property turbine rotors having blades that are diffusion bonded to a blade ring that is simultaneously diffusion bonded to a central hub.

Abstract: The disclosure relates to a turbine rotor and method of manufacture thereof. A plurality of blades having dovetails at the radially inner ends thereof are arranged in a circumferentially spaced circular array. A metallic hub is cast about the dovetails of said blades which are metallurgically bonded by the operation. Alternatively, the blades may be joined to the hub thereafter by an electron beam weld that extends axially to the rotor.

Abstract: In a steam turbine, a device for keying hubs of adjacent wheels together, wherein the wheels are not an integral part of the shaft of a rotor of the steam turbine and may be secured to the shaft by an interference shrink-fit at the surface of a bore through the hub of the wheel, comprises a substantially I-beam shaped key disposed in a keyway formed between adjacent hubs. A lip extends axially from the outer periphery of a pair of opposing end faces of adjacent hubs, the outboard surface of one lip of the pair of opposing end faces being in close proximity to the outboard lip of the other lip of the pair of opposing end faces. A respective pair of lands on each respective pair of opposing end faces defines a substantially radial slot respectively between the pair of lands. Streamlined fillets respectively transition the leading and trailing faces of each respective member of the pair of lands to the respective opposing end face.

Abstract: A turbine shaft structure of a multistage pump-turbine comprises at least two parts of upper and lower shaft parts generally connected at a runner portion of the highest pressure stage at which adverse external or internal effect is likely to be mostly applied. The runner portion of the highest pressure stage is provided with an axially vertical hole into which an upper end portion of the lower shaft part of the turbine shaft is inserted and the inserted upper end portion is welded to the wall of the vertical hole.

Abstract: The disclosed ceramic rotor comprises integrally formed blade portions made of ceramics sintered at atmospheric pressure and a blade-holding portion to which said blade portions are integrally cemented by ceramic material. The blade-holding portion is made of ceramics sintered at atmospheric pressure and has a larger density than that of the blade portions. The thickness of the blade-holding portion is not smaller than the thickness of the blade portions but smaller than the distance between the front and rear surfaces of the blade portions. In the disclosed process, bodies of the blade portions and the blade-holding portion are separately formed and coupled by applying ceramic material therebetween, and the coupled bodies are sintered at atmospheric pressure to produce the ceramic rotor.

Abstract: The disclosure relates to a turbine rotor and method of manufacture thereof. A plurality of blades having dovetails at the radially inner ends thereof are arranged in a circumferentially spaced circular array. A metallic hub is cast about the dovetails of said blades which are metallurgically bonded by the operation. Alternatively, the blades may be joined to the hub thereafter by an electron beam weld that extends axially to the rotor.

Abstract: An exhaust-gas turbocharger has a bearing system which is positioned between a compressor impeller and a turbine wheel which are positioned on respective ends of a rotor shaft. The compressor impeller is attached to the rotor-shaft via an intermediate bush. A conically mating fit, at one end of the intermediate bush directly adjacent to the bearing, serves to attach this intermediate bush to a shaft-stub of the rotor shaft. A frictionally-locked press fit serves, at the other end of the intermediate bush, to attach the compressor impeller to the intermediate bush, in a manner which transmits torque.

Abstract: Stress relief for the rim of an integrally bladed rotor made from a forging preform is provided by forming a plurality of radially extending circumferentially spaced-apart slots around the periphery of the preform. The slots are forged closed in a subsequent forming step. An oxide layer on the slot surfaces prevents the surfaces from bonding together when forged closed. The blades are formed between slots during the forging or by machining after forging.

Abstract: In a steam turbine, apparatus for preventing rotation of a first wheel with respect to a second wheel adjacent the first wheel, wherein the first and second wheels are secured to a shaft of a rotor of the steam turbine by an interference shrink fit, comprises a key disposed in a keyway defined by and between respective hubs of the wheels. The key is exposed to ambient environment of the rotor and is spaced from the axial ends of the keyway to permit steam to flow through portions of the keyway. Key and keyway configurations for prohibiting radial movement of the key are illustrated.

Abstract: Device for the containment of fragments of a fan ring in the event of burng of the ring.The fan ring comprises two cylindrical surfaces spaced axially and located radially inside of two containment rings of high tensile strength in the circumferential direction, engaged respectively in grooves of two parts of the rotor, located on either side of the fan ring.

Abstract: An impeller is assembled onto a turboshaft such that the impeller is deformed at its end walls so as to deform the inner wall of the hole of the impeller against the shaft such that the clearance between the shaft and the hole of the impeller is reduced to zero, thereby, preventing bending or offsetting of the shaft relative to the impeller. For causing the deformation of the shaft, washers with a circular projection are disposed on both sides of the impeller, with the projection facing the end walls of the impeller. The washers and the impeller are clamped by a nut which is screwed to the threaded end of the shaft, resulting in the projection being forced into the end wall of the impeller, thereby deforming the impeller.

Abstract: An arrangement for connecting a ceramic rotor wheel, particularly a turbine rotor wheel of a turbomachine, such as a gas turbine, to a metallic shaft. In order to obtain a primarily temperature-resistant (ceramic wheel-to-metal shaft) connection suitable for high speeds, the arrangement includes a thermal insulation ring seated on the shaft journal of a ceramic rotor wheel, on which there is mounted the tubular end portion of the metallic machine shaft, and which is then positioned on the shaft journal for positive connection through the intermediary of at least one fiber ring which is press-fitted onto the end portion of the shaft.

Abstract: A connector for connecting two rotors (2, 4) together, said connector having a plate (1, 3) on the end of each rotor.It has clamping bolts (5) and a plurality of fixing components (6) for the plates (1, 3). Each fixing component (6) has a sleeve (17) cut in two. The sleeve is cylindrical on the outside and conical on the inside and is disposed in precision-reamed bores (12, 14) of the same dimensions in the two plates, the bores of one plate facing and being situated exactly adjacent to those of the other when the rotors (2, 4) are aligned. A shank (20) which has a conical portion (21) pushes back the parts of the sleeve (17) against the walls of the bores (12, 14) thus connecting the plates together without play.In the case of normal operation, the connector has high resistance to shearing due to the fact that there are no stresses in the components (6). In the case of a torque greater than the normal torque, the parts of the sleeve 17 are deformed but can be very easily extracted.

Abstract: The disclosure relates to a process for the fabrication of low cost dual property turbine rotors having blades that are mechanically retained and a blade ring that is permanently bonded to a central hub.

Abstract: A rotor shaft assembly for use in turbochargers includes a metal shaft having a generally cylindrical female cavity therein concentrically distributed about the axis thereof; and a solid hubbed ceramic turbine wheel having a male stub shaft insertable into the female cavity. The axis of the male stub shafted ceramic turbine is coextensive with the axis of the shaft and the stub shaft is mated with the female receptacle and joined by an adhesive. A turbocharger includes a rotor-shaft assembly of the above-described type, in which the metal to ceramic adhesive joint is located in the turbocharger center housing.

Abstract: A turbine rotor structure is disclosed in which shrink-fitted turbine wheels are keyed to the turbine shaft to prevent rotation of the wheels with respect to the shaft in the event of any loosening of the shrink fit. In a preferred arrangement, the rotatable shaft of the turbine is provided with an integral flange, near one end, having two diametrically opposed, notched keyways formed at peripheral locations thereon. Each wheel of the set of wheels used to carry the turbine buckets includes an integral, central hub which extends axially to both sides of the wheel. Further, each hub has pairs of complementary keys and keyways whose members are axially opposite each other at peripheral locations on the wheel hubs. Thus, the key of the first wheel on the shaft mates with the keyway of the integral flange of the shaft and subsequently added wheels mate with each other.

Abstract: In an assembly including components clamped together and in which one or both of the components is subject to a relatively high and variable tensile stress, fretting due to vibration at abutting surfaces of the components can start cracks in the surfaces which is then accentuated in the stressed surface.FIG. 1 of the specification shows a fan turbine rotor disc 4 clamped on a shaft 2 by nut 12 and interposed between confronting surfaces 14 and 16 on the disc and an adjacent bearing is a stress-reducing collar 6 which is slotted at 18 to define struts 20 extending between the surfaces. The struts 20 transmit the clamping load while allowing torsional flexibility to reduce the shear stress and hence fretting between contacting surfaces.In an alternative embodiment the surfaces themselves may be slotted which gives the added advantage that the tensile stress in the surfaces can be reduced or eliminated.

Abstract: The disclosure relates to a composite turbine wheel comprising a hub having a plurality of radially extending blades thereon. The hub and blades comprise a plurality of discrete axially spaced layers of radially extending carbon fibers and circumferentially extending carbon fibers. Hoop strength is given to the hub of the turbine wheel by the circumferentially oriented fibers and radial strength is given to the blades by the radially oriented fibers. Transmission of shear loads between the radial and circumferential fibers is minimized.

Abstract: A bladed flow duct, for example in an axial flow turbo engine, is defined between two adjacent blades and the respective duct floor. In order to reduce secondary flow losses, the flow duct is provided with an arched zone (13, 13') projecting from the duct floor (10, 10') and extending along a portion of the suction side of the adjacent blade wall for producing a pressure rise or a reduction in the transverse pressure gradient over a relatively long forward and/or central portion of the duct as viewed in the flow direction (17) from the entrance end (21) to the exit end (22) of the duct. For this purpose the arched zone (13, 13') has a number of sections in the flow direction (17). A first section (23) starting in the entrance side of the duct is substantially or completely concave for causing said pressure rise. A second or central section (24) forms a convex peak and particularly a duct throat near the exit side of the duct. A third section (25) slopes down to the exit end (22).

Abstract: A unitary turbine wheel for a gas turbine engine, the turbine wheel including a pair of initially separate discs which are diffusion bonded together and define air passageways which extend radially through the discs. A plurality of initially separate turbine blades are provided each of which defines cooling air passageways, and the turbine blades are diffusion bonded in angularly spaced relationship to the peripheral surfaces of the discs with the air passageways in the blades communicating with the air passageways defined by the discs. Means is provided for drivably connecting the turbine wheel to a turbine shaft, and in a preferred embodiment, the turbine blades have a thermally insulating coating on the exposed surfaces thereof.

Abstract: A method of manufacturing a bladed element of a rotary fluid machine, for example a turbine or compressor, includes the steps of securing a plurality of blades in a gas-tight manner in respective openings in a wall of a hollow casing with one end of each blade in the hollow interior of the casing and the remainder of the blade externally of the casing, filling the casing with powder which surrounds the blade ends within the casing, hermetically sealing the casing, and isostatically pressing the casing around the blade ends in order to form the casing, the powder and the blade ends into a monolithic body.

Abstract: The invention relates to turbine wheels and in particular an improved way to form the connection between non-metallic turbine wheels and a metallic shaft. The resulting structure provides a secure connection therebetween, reduces tension loads otherwise placed on the non-metallic turbine wheel allowing higher rotational speeds and provides bearing and sealing areas.

Abstract: A hollow rotor shaft 34 having a bore 36 sealed by an end cap 40 is disclosed. The end cap abuttingly engages a first side 42 and second side 44 on the shaft which extend radially inwardly into the bore of the shaft. The sides face in opposite directions and are oriented in a generally axial direction. The end cap includes at least one dog 48, a cover 46 pressed tightly against the first side by the rotatable dog and a lock means such as the bolt 50. The dogs are rotatable to a first position during insertion and rotatable to a second position during assembly by the lock means which extends through the cover to permit assembly and disassembly of the end cap from the exterior of the rotor shaft. In one embodiment a gasket 72 is trapped between the side of the shaft and the cover by the side of the shaft and the cover.