Presentation on theme: "Wicket Gate Bushings Grease vs. Greaseless"— Presentation transcript:
1 Wicket Gate Bushings Grease vs. Greaseless Where's the grease??
2 Greaseless Bushing Applications 1. Linkage bushings2. Bearing3. Wear pads4. Wicket gate bushings5. Wicket gate bushings6. Packing wear strips7. Wicket gate bushings1. Bearing2. Linkage bushings3. Wicket gate bushings4. Wicket gate bushings5. Wear pads6. Trunnion bushings7. Trunnion bushings8. Wicket gate bushingsBushings, bearings, and wear pads will be known as “bushings”.Shift ring radial and thrust pads + wicket gate linkages and stem bushings.
3 Types of Greaseless Bushings MetallicNon-metallicOiles 500sp1-sl403(for hydro) does not contain graphite (PTFE/wax plugs with a little lead).
4 MAIN PROBLEMS: Stalling and Stiction (stick-slipping) Experience & ProblemsDelaminationPlug swellSlip-sticking from Lubron AQ30 on 6 units. 4 units have had gate stalling at high heads.Delamination of Thordon Traxl on 2 units. COE Hartwell plant and Ontario Hydro Canyon plant , too.Tight Thordon Traxl on 1 unit.MAIN PROBLEMS: Stalling and Stiction (stick-slipping)
5 Why?Slip-sticking from Lubron AQ30 on 6 units. 4 units have had gate stalling at high heads.Delamination of Thordon Traxl on 2 units. COE Hartwell plant and Ontario Hydro Canyon plant , too.Tight Thordon Traxl on 1 unit.
6 Why? Chatter Vibration Threshold Slip-sticking from Lubron AQ30 on 6 units. 4 units have had gate stalling at high heads.Delamination of Thordon Traxl on 2 units. COE Hartwell plant and Ontario Hydro Canyon plant , too.Tight Thordon Traxl on 1 unit.
7 Servomotor Pressure Monitor DISPLAYRealtime pressure (5 sec. update)Max. pressure in last 24 hour periodGraph of max. pressure per day for last 365 days.Graph of max. head per day for last days.Data storageWide area network4-20 maInstalled on 22 suspect units .View data at office or any location on WANRosemount mounted on wheel pit wall and connected to wicket gate servomotors’ existing taps in most units or in governor cabinet of some units.Rosemount Differential pressure transmitter
8 X-Y, Gate - Pressure Chart (Wet) AFTERBefore and after rebush.
9 X-Y, Gate - Pressure Chart (dry) Head and thermal considerations may change output slightly.
10 Future of Greaseless Options to consider: Greaseless materials “Green” grease and bronze*Standard greased bronze**Hybrid: install greased bronze for stem bushings and pads, use greaseless for linkages.
11 Consider for greaseless installation: Things toConsider for greaseless installation:Force – servomotorsFriction – coeff. of friction & headFatigue – will the material last?Is the friction (from the bushings and max. hydraulic head force) less than the sum of the servomotor’s force?Beware of pump-turbines!1. Pick a material that is strong and will hold together under harsh conditions.2. Material should have a low coefficient of friction. Ideally, the static and dynamic coefficients of friction should be close together to avoid “stick-slipping”.3. Material should have a low wear rate. Note, a material that is good in the wet may not be so good in the dry.4. Material should have low or no swell. At the very least , the swell must be predictable and allowances made.5. Don’t skimp on bushing clearances. Follow manufacturer’s recommendations.6. If your water quality is poor, consider installing seals. Silt and debris will accelerate wear.7. Study your unit. Take dry differential pressure readings and wet running readings at maximum head. Assume the friction will increase regardless of manufacturer’s data or laboratory tests. Are the servomotors strong enough for a 25% increase in friction? If not, continue using greased bronze or consider installing stronger servomotors.8. Accept that the life of the greaseless bushings will be less than the greased bronze.
12 OTHER CHARTS OF INTEREST APPENDIXOTHER CHARTS OF INTEREST
13 18 units with Thordon Traxl as stem and linkage bushings. 12 units with Lubron AQ30 as stem and linkage bushings.25 units with Lubron AQ30 as shift ring wear pads.2 units with Deva Glide as stem and linkage bushings.4 units with Deva BM as shift ring wear pads.2 units with Tenmat T814 feroform as shift ring wear pads.4 units at RM use Slip-ease as linkage bushings.29-72 month spread on re-bush.
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