GB2099923A

GB2099923A - Shaft lifting apparatus

Info

Publication number: GB2099923A
Application number: GB8117402A
Authority: GB
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1981-06-06
Filing date: 1981-06-06
Publication date: 1982-12-15

Abstract

A shaft lifting apparatus, particularly for lifting a power turbine shaft 18 of gas turbine power plant, for inspection and repair purposes, comprises a part ring-like frame (32) on which are mounted a number of rotatable contact elements (34), these elements preferably being in the form of cam followers. The frame is positioned under the shaft (18) to be lifted adjacent, for example, a split plain bearing which is to be replaced or if the shaft is to be lifted clear of the bearing to allow the shaft to be rotated easily. The bolts (40) of adjustable supports at each end of the frame (32) are rotated to bring the cam followers into contact with the shaft and to lift the shaft clear of the split plain bearing. <IMAGE>

Description

SPECIFICATION Shaft lifting apparatus This invention relates to an apparatus for lifting a shaft clear of a bearing. The invention is particularly directed to lifting the power turbine shaft of a gas turbine power plant clear of a plain bearing, but it can be applied to the lifting of any power transmission shaft.

Power turbine shafts commonly have a split plain bearing adjacent the blade carrying discs ofthetur- bine and a thrust bearing and another journal bearing adjacent the downstream end of the powertur- bine shaft. When the plain bearing has to be replaced, it is the usual practice to jack the power turbine and shaft assembly clear of the bearing so that the bearing and bearing can be dismantled and re-assembled with a new split bearing. The jacking arrangement can include a chain type flexible band which is placed underthe shaft and lifted in relation to the shaft housing.Such flexible bands do not allow the shaft to be rotated which would be advantageous when the blading of the power turbine has to be inspected, since the power turbine shaft has to be rotated for this purpose and at present the sliding friction in the plain bearings makes this a relatively difficult task.

The present invention seeks to provide an apparatus which enables a shaft, such as a power turbine shaft, to be lifted clear of a bearing which enables the shaft to be rotated easily and for a bearing, such as a split bearing, to be removed and replaced with relative ease.

Accordingly, the present invention provides a shaft lifting apparatus comprising a part ring-like frame member, a number of rolling contact elements mounted on the frame member and an adjustable support attached at each end ofthe frame member.

In use, the frame member is located underneath the shaft to be lifted adjacent the relevent bearing with the adjustable supports resting on a convenient stationary portion of the shaft support structure. The supports are adjusted to bring the contact elements into contact with the shaft and further adjusted to lift the shaft clear of the plain bearing. The amount by which the shaft is lifted clear of the bearing depends on whether the shaft is to be made easily rotatable or whether the bearing is to be removed. In the first instance, the amount need only be equal to half the diametral clearance between the shaft and the bearing. In the second instance, the top half of the bearing is removed before the shaft is lifted, and amount by which the shaft is lifted depends on how much clearance is required to remove the lower half of the bearing.

The frame member can be generally semi-circular in shape and the contact elements can be cam followers. The adjustable supports may be brackets, each having a bolt which in use can bear on a thrust washer on the stationary portion of the shaft support structure.

One or both of the brackets can be removed from the frame member, to allow the frame member to be inserted between the shaft and any adjacent stationary structure.

The present invention will now be more particularly described with reference to the accompanying drawings in which: Figure lisa diagrammatic layout of a gas turbine power plant having a power turbine, Figure 2 is a view to a larger scale of part of the power plant shown in Figure 1 showing part of the power turbine and shaft assembly with a split plain bearing.

Figure 3 is a section on line 3-3 in Figure 2 with a shaft lifting apparatus according to the present invention located between the shaft and a stationary structure ofthe power plant, and Figure 4 is a section to a larger scale on arrow 4 in Figure 3.

Referring to the Figures a gas turbine power plant 10 mounted on a base 12 comprises a gas generator 14, the exhaust from which drives a power turbine 16 and shaft 18. The shaft 18 is mounted in a split plain bearing 20 adjacent the blade carrying discs 22 of the power turbine, a thrust bearing 24 and another journal bearing (not shown) both at the downstream end of the shaft 18. The bearings 20, 24 and the other journal bearing are mounted in a stationiary support structure 26 which is also attached to the base 12. A cover 28 extends over the bearings 20, 24 and the shaft 18.

When the split plain bearing 20 has to be replaced or the shaft 18 has to be rotated for inspection of the power turbine blades, the cover 28 is removed so that the shaft lifting apparatus 30 shown in Figures 3 and 4 can be located in position.

The lifting apparatus comprises a generally ringlike frame member 32 on which a number of rotatable contact elements 34 are mounted. These contact elements are preferably in the form of cam followers.

At each end of the frame member, an adjustable support 36 is attached. Either or both of the supports 36 can be removed from the frame member, to allow the lifting apparatus to be inserted between the shaft 18 and the support structure 26. Each support comprises a bracket 38 and a bolt 40 which in use, bears on a th rust washer 42.

In orderto remove the parts ofthe plain bearing 20 without having to remove the whole of the power turbine and shaft from the power plant, the upper part of a bearing housing 44 and the upper half of the split plain bearing are removed, once the cover 28 has been removed. The lifting apparatus 30 is then inserted beneath the shaft, adjacent and downstream of a collar 46 integral with the shaft, either with or without removing one of the adjustable supports, depending on the clearance available on the shaft.

Thrust washers 42 are placed on the support structure beneath the bolts 40, and the bolts are then screwed down to lift the rotatable elements 34 on the The drawing(s) originally filed was/were informal andthe print here reproduced is taken from a Iaerfiled formal copy frame member 32 into contact with the shaft 18 and to lift the shaft clear of the lower half of the split plain bearing 20, to an extent sufficient to allow the lower half of the bearing to be removed and a new bearing half to be inserted. The amount of lift required will obviously tilt the shaft 18, but the thrust bearing 24 and the other journal bearing can accommodate this tilt and the lift amount is not great enough to cause any interference between the turbine rotor blades and the static vanes.

The lifting apparatus 30 is released by unscrewing the bolts 40, allowing the shaft to be lowered on to the new half ofthe plain bearing 20 and dropping the frame member so that the rotatable elements 34 are no longer in contact with the shaft 18. The apparatus 30 can than be removed from beneath the shaft 18.

The new upper half ofthe plain bearing can now be placed in position, and the upper part of the bearing fixed in position. The cover 28 is then replaced.

If it is only required to release the shaft 18 from the plain bearing 20, so that the shaft can be rotated for inspection of the turbine blading the lifting apparatus 30 can be used in the same way as described above, except that the shaft 18 is lifted only by an amount not exceeding half the diametral clearance between the shaft 18 and the bearing 20.

The shaft can then be rotated very easily by hand for inspection purposes.

Claims

1. A shaft lifting apparatus comprising a part ring-like frame member, a number of rolling contact element mounted on the frame member and an adjustable support attached at each end ofthe frame member.

2. A shaft lifting apparatus as claimed in claim 1 in which each contact element comprises a cam fol lower contactable in use with a shaft to be lifted.

3. A shaft lifting apparatus as claimed in claim 1 or claim 2 in which each adjustable support com prises a bracket having an adjustable bolt arranged in use to contact a stationary shaft support structure, the adjustment of the bolts bringing the contact ele ments into or out of contact with the shaft.

4. A shaft lifting apparatus as claimed in claim 3 in which a thrust washer is located between each bolt and the stationary shaft support structure.

5. A shaft lifting apparatus as claimed in any one of the preceding claims in which either or both of the adjustable supports can be removed to allow the lift ing apparatus to be located below the shaft.

6. A shaft lifting apparatus constructed and arranged for use and operation, substantially as herein described, and with reference to Figures 3 and 4 of the accompanying drawings.