Propellor thrust bearing

Details Propellor thrust bearing Propellor thrust bearing

1998-11-13

2001-01-09

Bucci, David A. (Department: 3682)

Bearings

Rotary bearing

Antifriction bearing

C384S563000

Reexamination Certificate

active

06170991

ABSTRACT:

FIELD OF THE INVENTION
The present invention generally relates to a bearing assembly. More particularly the present invention pertains to a thrust bearing assembly for a ship propeller.
BACKGROUND OF THE INVENTION
Known bearing assemblies used on a propellor of a ship are typically mounted on a shaft having several raised cylindrical portions which serve as bearing seats for a double-row spherical roller bearing and for the shaft washer of a spherical roller thrust bearing. The spherical roller bearing is mounted directly on the raised cylindrical shaft with a close fit, whereas the shaft washer of the spherical roller thrust bearing is mounted on another such raised portion, usually with a looser fit than the spherical roller bearing. Mechanisms are also provided which, from the outside, urge the housing washer and the set of rollers against the shaft washer. To obtain a correct distance between the two bearings, a spacing ring has been used. The spacing ring is positioned in a deeper portion of the shaft between the two bearing seats, and for this reason the spacing ring has to be split.
The shaft provided with several such raised portions requires a time-wasting and expensive machining during manufacture of the shaft. Problems also arise during mounting and especially at dismounting of such a bearing assembly. The complex structural design means that dismounting requires many different tools and aids. At the same time, the bearing exchange and over-hauling must often be effected during hard working conditions in the ship.
In light of the foregoing, a need exists for a thrust bearing assembly, such as a propellor thrust bearing assembly, and a method of mounting such a bearing assembly that are not susceptible to the same disadvantages and drawbacks as other known thrust bearing assemblies and mounting methods.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a propeller thrust bearing assembly includes a housing surrounding a shaft, a spherical rolling bearing provided on the shaft and abutting against a shoulder provided on the shaft, and a spherical thrust bearing comprised of a shaft washer fitted on the shaft, a housing washer provided in the housing, and a set of rolling bodies provided between the shaft washer and the housing washer. A spacing sleeve is provided between the spherical rolling bearing and the spherical thrust bearing, and a lid member is mounted around the shaft and adapted to urge the housing washer against the set of rolling bodies and via the rolling bodies against the shaft washer. The axial distance between the spherical rolling bearing and the spherical thrust bearing is such that respective force lines meet at a point situated on the center axis of the shaft. The spherical rolling bearing has a taper bore and is mounted on a withdrawal sleeve that is positioned on the shaft. The spacing sleeve has internal threads and is screwed onto an external thread on the withdrawal sleeve. A tubular member is arranged about the shaft to keep the shaft washer pressed against the end of the spacing sleeve facing away from the spherical rolling bearing, and this tubular member is secured in position by a locking nut screwed onto threads on the shaft.
According to another aspect of the invention, a propeller thrust bearing assembly includes a spherical rolling bearing mounted on a shaft and abutting against a stop provided on the shaft, and a spherical thrust bearing comprised of a shaft washer fitted on the shaft, a housing washer, and a set of rolling bodies located between the shaft washer and the housing washer. A spacing sleeve is located between the spherical rolling bearing and the spherical thrust bearing to space the spherical rolling bearing from the spherical thrust bearing, with the spacing sleeve including an internal thread engaging a threaded portion on the shaft. A lid member is adapted to axially urge the housing washer towards the set of rolling bodies.
A further aspect of the invention involves a process for dismounting a propeller thrust bearing assembly mounted on a shaft. The assembly includes a spherical rolling bearing provided on the shaft and abutting a shoulder, a spherical thrust bearing comprising a shaft washer fitted on the shaft, a housing washer provided in a housing surrounding the shaft and a set of rolling bodies provided between the shaft washer and the housing washer, a spacing sleeve provided between the spherical rolling bearing and the spherical thrust bearing, and a lid member disposed on the shaft and adapted to urge the housing washer against the set of rolling bodies and the rolling bodies against the shaft washer. The axial distance between the spherical roller bearing and the spherical thrust bearing is such that the force lines meet at a point situated on a center axis of the shaft. The spherical rolling bearing has a taper bore and is mounted on a withdrawal sleeve, and the spacing sleeve has internal threads and is screwed onto an external thread on the withdrawal sleeve. A tubular member is arranged about the shaft and is adapted to keep the shaft washer pressed against a rear end of the spacing sleeve facing away from the spherical rolling bearing. The tubular member is secured in position by a locking nut screwed onto threads of the shaft. The dismounting process involves unscrewing the looking nut, axially pulling out the lid member and the housing washer, axially removing the shaft washer and the set of rolling bodies to expose the outwardly facing surface of the spacing sleeve, and thereupon screwing the spacing sleeve in a direction tending to cause the spacing sleeve to move towards the spherical roller bearing so that the thread engagement between the withdrawal sleeve and the spacing sleeve causes the withdrawal sleeve to be pulled axially outwards from its position within an inner race ring of the spherical rolling bearing with the clamping function of the inner race ring on the withdrawal sleeve ceasing, and with the spacing sleeve together with the withdrawal sleeve and the spherical rolling bearing being pulled off the shaft.


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