SNAP RING INSERTION. TOOL FOR AUTOMATIC TRANSMISSIONS

BACKGROUND OF THE INVENTION 1. Field of the Invention

The subject invention relates generally to hand tools and, more particularly, to a snap ring insertion tool for quickly and easily installing and removing snap rings in automatic transmissions such as the Ford E40D transmission .

2. Description of Related Art

In the prior art, tools have been provided for installing snap rings in transmissions. The known tooling provided for installation of the overdrive snap ring in the Ford E40D transmission comprises a number of separate parts which must be laboriously assembled and reassembled three times during the removal and installation process in order to complete the desired operations. In particular, the conventional tool includes nine separate pieces, including a large cross-bar, a small cross-bar, a handle, an O-ring, a disc plate, three bolts, and a washer. These parts must be assembled at the outset of the operation and reassembled several times during operation.

In using the conventional tool, the center support outer snap ring is first removed by applying downward pressure on the center support piston, allowing the rebuilder to manually remove the outer snap ring. In a separate operation from the first, the rebuilder must

disassemble the tool and reassemble it to remove the overdrive snap ring from the center support piston, then again disassemble the tool. The rebuilder must then reassemble the tool to install the overdrive snap ring into the center support piston, then disassemble the tool and place the center support piston down into the transmission casing. The conventional tool must then be reassembled with two other parts in order to install the center support piston, after which the tool is disassembled and all its pieces stored into a container.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of the invention to provide improved tooling for servicing transmissions;

It is another object to provide a single-piece tool for performing operations requiring repeated reassembly of tool parts in the prior art;

It is another object of the invention to provide an improved one-step operation snap ring installation tool;

It is another object of the invention to provide such an installation tool which can also automatically install an overdrive snap ring into a center support piston;

It is a more particular object of the invention to provide a tool which quickly assists in installing and/or removing the outer center support piston snap ring in the Ford E40D transmission;

It is a further object of the invention to reduce the installation labor time involved in removing and/or installing snap rings in automatic transmissions and, particularly, the Ford E40D transmission; and

It is another object of the invention to meet the foregoing objects with a tool which is durable, as well as lightweight .

These and other objects of the invention are accomplished by provision of a single tool operative on the bevel spring, center support piston, and overdrive snap

ring of the transmission. The tool includes a means for depressing the bevel spring, for depressing the center support piston, and for installing the overdrive snap ring. In the disclosed embodiment, the means is formed by the peripheral edge structure of a disc plate which may be driven downward by a cooperating actuator mechanism so as to cause automatic depression of the bevel spring and the center support piston.

BRIEF DESCRIPTION OF THE DRAWINGS The objects and features of the present invention, which are believed to be novel, are set forth with particularity in the appended claims. The present invention, both as to its organization and manner of operation, together with further objects and advantages, may best be understood by reference to the following description, taken in connection with the accompanying drawings .

Figure l is a perspective of a preferred embodi¬ ment according to the invention; Figure 2 is a bottom view of the disk plate member according to the preferred embodiment ;

Figure 3 is a side sectional view of the disk plate member of Figure 2 taken at 3-3 of Figure 2;

Figure 4 is a top view of the cross-bar member according to the preferred embodiment;

Figure 5 is a side sectional view taken at 5-5 of Figure 4 ;

Figure 6 is a partial side elevational view of the twist T-bar tip according to the preferred embodiment; Figure 7 is a side elevational view of a shaft pin according to the preferred embodiment;

Figure 8 is a partial schematic side sectional view useful in illustrating operation of the preferred embodiment; and

Figure 9 is a partial schematic side sectional view further useful in illustrating operation according to the preferred embodiment

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description is provided to enable any person skilled n the art to make and use the invention and sets forth the best modes contemplated by the inventors of carrying out their invention. Various modifications, however, will remain readily apparent to those skilled in the art, since the generic principles of the present invention have been defined herein specifically to provide an easily usable, durable, and readily anufacturable multiple function snap ring insertion tool Figure 1 illustrates a snap ring insertion tool according to the preferred embodiment, including a twist T-bar 17 tnreadaoly mounted m a cross-bar or cross-member 13 The T-bar 17 has a solid, threaded metal stock shaft 73, a conical tip 75,

First and second shaft pins or "shoulder bolts"

19, 21 are mounted slidably through the top surface 20 of the cross-bar 13 and tnreaded into a disk plate 15 The snoulder bolts 19, 21 are thus "free floating" vertically with respect to the cross-bar 13

The cross-bar or cross-member 13 further includes first and second generally rectangular flanges 22, 24 through which are threaded first and second bolts 23, 25 Rectangular beveled surfaces 16, 18 lead from the inner edges of the respective flanges 22, 24 to the rectangular top surface 20 of the cross-bar 13 The cross-bar 13 and disc plate 15 may be constructed, for example, of T-6 billet aluminum, while the T-bar 17 and bolts 19, 21 may be mild steel and stainless steel, respectively.

As further shown in Figure 1, the disk plate 15 includes a conical depression 27 for receiving the mating conical tip 75 located at the end of the threaded shaft 73 of the twist T-bar 17. Thus, when the handle 71 of the twist T-bar 17 is rotated in the appropriate direction, the shaft 73 progresses downwardly and forces the disk plate 15 in the same downward direction When the twist T-bar 17 is rotated in the opposite direction, the disc plate 15 is permitted to move closer to the cross-bar 13, guided by the shoulder bolts 19, 21.

As shown particularly in Figures 2, 3, and 9, the disk plate 15 includes a peripheral edge structure 28 of uniform cross-section around the entire circumference 30 of the disk plate 15. This peripheral edge structure 28 includes a depending bevel spring depressor ridge 29 of generally rectangular cross-section. The inside vertical linear edge of the depressor ridge 29 leads to a first squared-off depression 31 which, with a second depression 35 of generally rectangular cross-section, defines a snap ring installer ridge 33 As may be seen, the snap ring installer ridge 33 is also generally rectangular in cross- section, extending downwardly parallel to the bevel spring depressor ridge 29, but to a considerably lesser extent. The second depression 35 is dimensioned to accept and mate with a cooperating portion of the center support piston of an automatic transmission, as will be described m further detail below m connection with Figure 9.

Figures 4 and 5 illustrate details of the preferred cross-bar 13. The cross-bar 13 includes a center tapped hole 59 which threadably receives the threaded shaft 73 of the twist T-bar 17, and first and second through holes 55, 57 for slidably receiving the shafts of the shaft pins or shoulder bolts 19, 21. Respective holes 51, 53 are formed in the respective flanges 22, 24. These holes are oblong or elliptical in shape, rather than cylindrical, in order to accommodate the tolerances in the positioning of cooperating bolt holes within the transmission case, as

further described below. Appropriate dimensioning permits attaching the cross-bar 13 to as many as three different bolt locations in a transmission case. Hole 51 may be, for example, .674-inch in length L, and .191-inch m width W, while hole 53 may be 1.3 inches m length L and .179-inch in width W. The overall length of the cross-bar 13 may be, for example, 10-3/8 inches, with the center tapped hole 59 being .50-inch in diameter. The distance between the centers of holes 55, 57 may, for example, be 4.111 inches. Figure 6 shows the conical tip 75 at the end of the twist T-bar 17 in further detail. The tip 75 is preferably rotatably mounted in and spins freely with respect to its shaft 76. The shaft 76 may be press-fitted into the shaft 73 or attached by other means such as a spring-loaded ball snap-in mechanism similar to "Snap-On™" tools. The tip design will not scar or damage the anod zed aluminum surface of the disk 15, spins freely, and is hardened to prevent wear. Its design further serves to center or register the disk plate 15 into position. Figure 7 shows a further detail of a shaft pin or shoulder bolt, e.g., 19, 21 The shoulder bolt includes a hexagonal pin head 81, a pin shaft 83, and a threaded tip 85. The threaded tip may be of a length o , for example, .375-inch. The hexagonal head 81 permits torquing down of the threaded tip into suitable holes in the disk plate 15.

Installation and use of the insertion tool according to the preferred embodiment will now be described in more detail in connection with Figures 8 and 9. As shown in Figure 8, the cross-bar 13 sits on the top surface 103 of the inside shoulder 105 of the transmission casing and mounts to the bolt holes which are tapped around the shoulder 105. This mounting is achieved in the preferred embodiment by installing bolts 25 through the flange, e.g., 24 and into the casing bolt hole, e.g. , 101. In this position, the groove 35 of the disk plate 15 mates with the corresponding surface 90 of the center support piston 91 of the transmission, as shown in Figure 9.

In Figure 9, the overdrive snap ring 97 has been placed around the center support piston 91 and has been moved downward about the piston 91 to a position in which the snap ring installer ridge 33 contacts the overdrive snap ring 97 and is positioned to force it down towards the case ring groove 99 where it is to be installed. Further in this same position, due to the dimensioning, the bevel spring depressor ridge 29 is contacting the bevel spring 95. The bevel spring 95 is a return spring which keeps the overdrive (center support) piston 91 in a downward position when the piston 91 applies the overdrive clutch. Then, when the overdrive piston is released, the bevel spring 95 pushes downward.

Dimensioning of the disk plate 15 is, of course, driven by the dimensions of the transmission with which it cooperates, as those skilled in the art will appreciate. Exemplary dimensions in the preferred embodiment with reference to Figure 9 are d. = .747, d ₂ = .415, d ₃ = .236, d, = .104, d ₅ = .213, d _fi = .256, and d ₇ = .104, all in inches.

Once in the position shown in Figure 9, the twist T-bar 17 is manually rotated downward through the cross-bar 13 manually or by a torque wrench, thereby applying pressure onto the center of the disk plate 15. The disk plate 15, in turn, simultaneously pushes down the bevel spring 95 and the center support piston 91 while pushing the overdrive snap ring 97 into place. When h<= torque wrench reads 65 foot-pounds, the outer center support snap ring 93 must be manually installed into the housing via a screwdriver or flat blade, all in one operation.

As those skilled in the art will appreciate, the preferred tool 11 finds particular application in removal of the center support piston 91 and in installation or reinstallation of the center support piston 9 ₁ and overdrive snap ring 97. A more detailed description of these removal and installation operations with the preferred tool follows.

Removal of the Center Support PiBton

To remove the center support piston 91, the insertion tool 11 is first inserted down into the inner portion of the transmission casing, and the cross-bar 13 is placed over the top of the center support piston 91 and across the flat shoulder 105 of the transmission casing

(Figure 8) . The two bolts 23, 25 are then placed through the slots 51, 53 of the cross-bar 13 and into the existing bolt holes, e.g. 101, in the shoulder 105 of the transmission casing. The bolts 23, 25 are then manually wrenched downward until firmly tightened.

With one hand, right or left, the rebuilder next takes a firm hold of the T-bar handle 17 and manually begins twisting the handle 17 downward, applying pressure to the disc plate 15, thereby relieving pressure against the center support snap ring 93

to apply 65 foot-pounds of pressure to the T-bar handle 17, until pressure is completely off of the center support snap ring 93. A screwdriver or flat bar is then used to manually loosen the end of the center support snap ring 93. The remaining portion of the snap ring 93 is then manually pulled away and out of the snap ring groove. Once the snap ring 93 is completely clear of its groove, the snap ring 93 is completely pulled out of the transmission casing. The T-bar 17 is then twisted in the opposite direction to relieve the pressure on the disc plate 15 and cross-bar 13. The two bolts 23, 25, which fasten the cross-bar 13 to the transmission casing, are manually unscrewed, and either the right or the left hand used to grasp the T-bar handle 17 and lift the tool 11 out of the casing. The center support piston 91 may then be removed by manually sliding it out of the casing.

Installing the Center Support Piston, and Overdrive Snap Ring To install the center support piston 91 and overdrive snap ring 97, the center support piston 91 is first inserted into the pump housing and lowered until it is seated against the lower spring located in the housing (not shown) . The center support outer snap ring 93 is then inserted into the pump housing and around the outside of the center support piston 91. The bevel spring 95 is then inserted on top of the center support piston 91. Next, the overdrive snap ring 97 is placed on top of the bevel spring 95 and around the inner wall of the center support piston 91. The insertion tool 11 is then lowered into the interior of the transmission casing, and the cross-bar 13 is placed over the top of the center support piston 91 and across the shoulder 105 of the casing. The two bolts 23, 25 are again placed through the slots 51, 53 of the cross¬ bar 13 into the existing bolt holes in the shoulder 105 of the pump housing and manually wrenched downward until firmly tightened. One hand is then used to take a firm hold of the T-bar handle 17 to twist the handle 17 downward, applying pressure to the disc plate 15, again using either judgment or a torque wrench to apply 65 foot¬ pounds of pressure to the T-bar 17. The T-bar handle 17 is twisted downward until a clicking sound is heard, which signals that the overdrive snap ring 97 has been installed. Using a screwdriver or flat bar, the center support piston outer snap ring 93 is then pushed downward and into place until another clicking sound is heard. After installation of the overdrive and outer snap rings 93, 97, the pressure on the center support piston 91 is manually relieved by twisting the T-bar handle 17 in the opposite direction. The two bolts which fasten the cross-bar to the transmission casing are then unscrewed and, with one hand, the T-bar handle 17 and tool 11 are lifted out of the pump housing. The shaft pins 19, 21 which are running through the cross-bar 13, guide the disk

plate 15 up and down, keeping it in alignment during these operations .

Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiment can be configured without departing from the scope and spirit of the invention. For example, various hydraulic, pneumatic, or power assist mechanisms could be used to control the up and down movement and positioning of the disc plate 15 as alternatives to the T-bar mechanism presently preferred. Various configura¬ tions of cross-members can be designed and various conventional fastening mechanisms applied to hold a cross- member or other disc plate driving mechanism in position with respect to the transmission. While the particular preferred embodiment has been designed to operate with the E-40D transmission, its adaptation to similar applications will be apparent from the above disclosure. Therefore, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described herein.