Excavating – Cable-operated – Boom-type
Reexamination Certificate
1998-03-11
2001-06-05
Pezzuto, Robert E. (Department: 3671)
Excavating
Cable-operated
Boom-type
C180S009100
Reexamination Certificate
active
06240661
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to power mining shovels, such as those used for surface mining. The invention also relates to the splined connection of a rotating shaft and a member that either drives or is driven by the shaft.
A typical power mining shovel includes a revolvable upper frame supported on a mobile carbody. The manner in which the carbody is supported is described below. A fixed boom extends upwardly and outwardly from the frame, and a dipper handle is mounted on the boom for movement for pivotal and translational (non-pivotal) movement relative to the boom. A dipper is fixed to the end of the dipper handle. The outer end of the boom has thereon a sheave, and a hoist cable or rope extends over the sheave and is fastened to the dipper.
The carbody is supported by ground-engaging means, such as crawler track assemblies. A typical crawler track assembly includes a series of shoes that are pivotally pinned together and that have shoe drive lugs which are engaged and pushed by a rotating drive tumbler. The drive tumbler is mounted on a rotating tumbler or drive shaft and has a sprocket-like shape including tumbler lugs that extend radially outward and engage the shoe drive lugs as the tumbler rotates, thereby driving the shoes and moving the crawler track around its endless path. Each crawler track assembly is driven by a motor via a drive train.
U.S. patent application Ser. No. 08/922,838, which was filed Aug. 26, 1997, which is assigned to the assignee hereof, and which is incorporated herein by reference, discloses a disc brake apparatus for such a drive train. The disc brake apparatus includes a brake hub having internal splines engaging external splines on a transmission input shaft. Engagement of the disc brake apparatus prevents rotation of the brake hub which in turn prevents rotation of the input shaft, thereby braking the entire drive train. Obviously, a substantial amount of torque is transmitted by the splines on the brake hub. This can cause these splines to wear out before other components of the drive train.
It is known to “rebuild” the splines by machining the brake hub and providing an insert having thereon new splines.
FIG. 1
illustrates a prior art insert
10
in a brake hub
14
. The insert
10
has a flange
18
through which screws
22
(only one is shown) and dowels or pins
26
(only one is shown) extend to secure the insert
10
to the hub
14
.
SUMMARY OF THE INVENTION
One disadvantage of this prior art arrangement is that the load distribution between the insert and the hub is uneven because all of the load is transmitted through the insert flange. Also, machining of the prior art insert is relatively complicated and expensive.
The invention provides an improved spline insert and an improved method of rebuilding a brake hub. Preferably, the insert and the hub are connected by a plurality of pins extending into holes spaced around the junction of the insert and the hub. In other words, the holes overlap both the insert and the hub, so that one side of each pin engages the insert and the other side of each pin engages the hub. The holes extend along most of the width (the distance in the direction of the axis of rotation) of the insert. The load is distributed along the entire length of the pins and is not concentrated in one area of the insert. The insert flange is needed only to locate the brake hub. The flange could be eliminated entirely in other embodiments of the invention in which another mechanism is used to located the hub.
Because the pins engage the insert along most of the width of the insert, the load distribution is more even.
Machining is substantially reduced by eliminating the tapped holes and reducing the flange size. The flange size can be reduced because the pins do not extend through the flange.
Because the pins do not extend through the flange, the outside diameter of the insert can be greater, resulting in a more robust construction.
The pins “captivate” the brake hub, thereby eliminating the need for screws.
The pins can be ground or machined flush with the end of the insert, adjusting for any machining errors.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings.
REFERENCES:
patent: 3580345 (1971-05-01), Brown
patent: 3994352 (1976-11-01), Siorek
Earl Lowe, Jr. James
Harnischfeger Technologies Inc.
Pezzuto Robert E.
Price David R.
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