HG Bearing

Slide Bearings Series H For Shaft Diameter Range 250 - 560 mm Main Application Field Horizontal Hydroturbine Generators

Slide Bearing Type HG

RENK slide bearings type HG have been specifically designed for horizontal hydro turbine generator applications.

The HG bearing is a fully selfcontained, oil sump lubricated, slide bearing. It is designed to cope with the high axial overloads and overspeed conditions, also „black starts“ encountered in such applications.

This brochure contains the data required for incorporating HG slide bearings into machine designs. It also explains the unique features incorporated in the HG bearing.

Technical Information

The RENK horizontal slide bearing type HG is a clever design, specifically developed in its combined thrust and journal form to meet the requirements of the horizontal shaft hydro turbine generator application, when water cooling is the preferred option.

The HG bearing is fully self contained, water cooled, with its lubricating oil positively circulated by an internal viscosity pump powered by a rotating shaft collar.

When the head of water powers the turbine, and the machine shaft rotates, the HG bearings start to operate all on their own (independent of any external pumps etc.). They continue to operate safely under normal duty conditions (and overspeed duty) until the shaft runs down to rest.

Bearing Housing The top and bottom half housings are cast iron, but can be nodular cast iron or cast steel if specified.

The bottom half housing incorporates two large „U“ tube coolers in such a way as to give maximum water cooling efficiency. There is a heavy centre section to the bearing housing that is bored out to form a spherical seating for the bearing shell.

Bearing Shells The shells are manufactured from steel (C 10) and have a spherical seating. They are lined with RENKmetal therm 89 and have a plain cylindrical bore. Two lobe bore shells also available.

For the high thrust (axial) loads, elastically supported circular tilting pads (RD thrust pads) are fitted in the ends of the shell (type...A).

The cup springs supporting the RD thrust pads have damping properties which can elastically absorb axial hammering forces from the water turbine, without detriment to the whitemetal working surfaces or the equally important pivoting action of the pads.

The displacement of the very same cup spring moutings can be utilised to calculate the magnitude of the axial load imposed on the RD thrust bearing. Thus the standard bearing has a built-in thrust

2

metering system that could also be used as a safety trip for a machine prone to dangerously high (above design limit) thrust surges.

Displacement of the cup springs (the support of each RD thrust pad) ensures that the thrust load is safely carried by the full surface of the thrust bearing at all times.

Because of the unique arrangement of the shrouded RD thrust bearing, every RD thrust pad is assured of its very own cooled oil supply; even the thrust pads at the top of the thrust ring. Thus there is no danger from individual thrust pad failure due to oil starvation.

RD thrust pads at both ends of the bearing shell are identical. If one is accidentally damaged on site, it can be easily replaced by one other from stock. Spare pads come individually protection packed for ease of storage.

The journal shell itself is spherically seated, bolted together and located in the bearing housing in the same well proven manner used by RENK in their world renowned E range bearings. This, coupled with a very high quality of dimensional and geometrical finish guarantees that every shell gives the very best performance and is fully interchangeable.

Oil Supply The HG bearing is fully self contained with its own large oil sump, cooled by two large and highly efficient water coolers (connected in series), one each end of the bearing.

A viscosity pump, powered by the periphery of one of the thrust collars lifts a copious supply of oil from the oil sump direct to all the working faces of the bearing. In fact there is so much oil available from the viscosity pump that the excess is directed to cascade to move as much of the oil sump as possible over and between the water cooler tubes, while at the same time taking away an extra amount of heat from the bearing shell.

A specially devised weir system in the top half shell (at the point of

oil entry from the viscosity pump) ensures that both thrust faces, as well as the journal, get a rapid delivery of oil at start-up.

Thermocouple access to selected RD thrust pads at each end of the bearing shell is provided in the top half housing.

Heat Dissipation

Commercially available thermosensors can be used for monitoring temperatures. We recommend the use of RENK resistance thermometers, alternatively, RENK angle thermometers for direct visual reading.

Frictional heat generated by the HG bearing is dissipated through two large „U“ tube coolers. These finned tube (CuNi10FeM1) coolers are fully submerged in the oil sump, one each end of the bottom half casing. The internal design of the bearing controls the flow of the oil in circulation to ensure that these water coolers operate with maximum efficiency.

Seals Cast iron baffles and rigid seals (type 20) combine to give an effective oil sealing arrangement for the HG bearing. These rigid seals are made of corrosion resistant aluminium alloy and they correspond to protection grade IP 44.

Standard seals of higher protection grades are available upon request. Being of a standard form, used on other RENK slide bearings, spares are always readily available from stock.

Temperature Control Provision is made for measuring the temperature of the bearing shell through a standard drilling and tapping on the side of the bottom half housing.

Type Housing Heat

dissipation

Shape of bore

Generally, any branded oil of low foaming tendency can be used as a lubricant. The correct viscosity for each operating condition will be determined by EDP calculation.

Such calculations are always carried out at the design stage. A computer print-out of the results can be provided on request.

One Direction of Rotation Because of the tangential delivery discharge from the viscosity pump, the HG bearing can only operate in one direction of rotation. Therefore, to ensure the bearing is supplied with water connections, oil level gauge and instrumentation suitable for site layout, it is important to have a key plan of the machine, showing shaft rotation and connections, when an order is placed.

H G = smooth housing    

N = natural cooling W = water cooling (cooling tubes in oil sump) F=

and type of lubrication

Thrust parts

Oil Selection

    

plain cylindrical bore, with fixed oil ring

Q = without thrust parts (non-locating bearing) A = elastically supported circular tilting pads (locating bearing)

Example for quoting a slide bearing type HG, smooth housing, water cooling with cooling tubes in oil sump, plain cylindrical bore with fixed oil ring, elastically supported circular tilting pads as locating bearing, size 35, shaft diameter 355 mm:

H G WF A

35 - 355

Dimensions of Bearings

Dimensions in mm Size

28

35

45

56

Shaft Ø D 250 280 3001) 3151) 3351) 3551) 300 315 335 355 3751) 4001) 4251) 4501) 375 400 425 450 4751) 5001) 5301) 5601) 475 500 530 560 6001) 6301) 6701) 7101)

B1

220

b1

562

b2

680

b3

d1

d2

400

80 80

276.2

465 485 250

730

792

342

615 320

760

830

394

770 410

upon request

90 90 90 90

112 112 112 112

d3

d4

e1

e2

h1

h2

h3

l1

55 for M 42

20,5

990

300

560

960

75

1120

62 for M 48

20,5

1030

390

670

1110

85

1165

70 for M 56

25,5

1300

560

750

1375

110

1430

140 140 140 140

1) non locating bearing

3

Sales Organisation

Export

Hannover Heidelberg Mönchengladbach

Australia Austria Belgium Brazil Canada Czech Republic Croatia Finland France

G.B. and Ireland Hungary India Italy Japan Liechtenstein Luxembourg Mexico Netherlands

Norway PR China Slovak Republic Slovenia Republic South Africa South Korea Spain USA

Headquarters and Manufacturing Plant

Assembly and Distribution Centers with Sales and Engineering Support

RENK AKTIENGESELLSCHAFT Werk Hannover Weltausstellungsallee 21 D-30539 Hannover Telephone: (5 11) 86 01-0 Telefax: (5 11) 86 01-288 e-mail: renk_hannover@renk.de

RENK Corporation 304, Tucapau Road 29334 Duncan S.C. USA Telephone: (1-8 64) 4 33 00 69 Telefax: (1-8 64) 4 33 06 36

MAN B&W (Japan) Ltd. Hibiya Park Building (R. 410) 1-8-1, Yurakucho Chiyoda-ku, Tokyo 100-0006 Japan Telephone: (81-3) 32 15-1310 Telefax: (81-3) 32 84-0867

We reserve the right to changes made in the interests of technical improvement.

RH-1189 (7.99) Printed in Germany

Domestic