A wicket gate bushing supports the stem of a vane that regulates water entering a hydro turbine. Wicket gates are also called guide vanes; drawings may therefore specify a guide vane bushing. During an overhaul, wear or difficult gate movement may raise a replacement question. The answer depends on the gate assembly, not one removed sleeve.
This article concerns gate-stem bushings and related mechanism positions. The turbine guide bearing supports the main rotating shaft and is a different part. JEDBUSHING manufactures custom hydropower bushings to drawings for OEM and overhaul batches.
Where Do Wicket Gate Bushings Support the Vane?
Each wicket gate pivots around its stem as the linkage moves it. Depending on the turbine, the stem may have upper, intermediate, and lower supports in the head cover and bottom ring. Linkage pins can also have bushings, but they are separate parts with different duties.
Identify the unit, gate station, position, and original item number before discussing size. Mark each removed sleeve by its installed position; an upper sleeve cannot identify every part in the assembly.
Which Signs Suggest Bushing Wear?
Scoring, loose fit, or a worn gate stem calls for closer inspection. A gate that sticks or needs high force to move may also prompt a bushing check. But inadequate grease, corrosion, debris, linkage problems, and facing-plate contact can cause similar behavior.
Changes in closed-gate gaps provide another clue. If one gate no longer lines up with its neighbors, check the stem support, linkage, and sealing edges. Leakage can involve gate adjustment, facing plates, and thrust surfaces. A new sleeve cannot correct an out-of-line housing or damaged journal.
Before dismantling, record the affected gate, wear location, stem condition, lubrication history, and evidence of water or grit entering the support. Compare it with neighboring gates. If automatic greasing is fitted, check delivery at each point; pump pressure alone does not prove every bushing received grease.
Which Clearances Should Be Measured?
The phrase “wicket gate clearance” can describe several different gaps. The bushing-to-stem running clearance is the fit between the installed bushing bore and its gate journal. Measure the journal and housing as well as the old bore; wear may have changed all three. The drawing must say whether a dimension is measured before installation or after final boring. Also distinguish diametral clearance, the bore minus the journal diameter, from the one-sided radial gap when the stem is centered.
The heel-to-toe clearance is the gap between neighboring gates when closed. The gate-to-facing-plate clearance is the gap at the upper or lower end of a gate. These are assembly and sealing measurements, not the bushing’s running clearance. They can help reveal misalignment, linkage wear, or gate thrust wear, but cannot be copied into a bushing purchase specification.
Record each measurement point and compare it with the OEM drawing and earlier outages. The U.S. Bureau of Reclamation’s hydro maintenance guidance treats gate and facing-plate gaps separately. A web chart cannot establish whether an unknown unit needs new bushings.
What Must Be Confirmed Before Making a Replacement Bushing?
First confirm the original construction and lubrication. Some wicket gate bushings use greased bronze; other designs use engineered self-lubricating materials. A drawing may specify a particular bronze grade, groove layout, graphite inserts, seals, or mating journal finish. Changing to a different bearing material is a design decision for the equipment owner and engineer, not a shortcut based on a product photo. JED can review tin bronze or graphite-plugged bronze designs when specified for the application.
Next establish the final geometry. Record each stem journal diameter and condition, the housing bore, sleeve length and flange or shoulder features, oil passages, interference fit, and required installed bore. If the plant will restore a worn journal or finish-machine the assembly, the approved production drawing must reflect that plan. An old bushing can help identify features, but its worn bore is not automatically the correct new dimension.
Send Your Wicket Gate Bushing Drawings for Batch Review
JEDBUSHING manufactures made-to-drawing bronze bushings and machined copper-alloy parts for hydro equipment. For an OEM run or scheduled turbine overhaul, send your drawings and batch requirements. Include the turbine model, gate count, bill of materials, part numbers and revisions, quantities by position, bronze or self-lubricating specification, journal and housing data, and inspection requirements.
If the original drawing is incomplete, send available drawings, photos, and measurements with the proposed restoration and final-machining plan. We can review what needs confirmation before quoting the batch. The approved design and site measurements determine the finished part; JED manufactures the agreed components.
FAQ
Are upper and lower wicket gate bushings interchangeable?
Do not assume so. Length, outside fit, installed bore, lubricant features, seals, and mounting details may differ. Order each position against its own approved item number and drawing revision.
Can bushings be supplied with material for final line boring on site?
They can be specified with an allowance if the approved drawings define the supplied bore and final installed dimensions. State which positions will be bored together so manufacturing and inspection match the site’s installation plan.
Can you mark different bushing types within a production batch?
Position or part-number marking and separate packing can be reviewed with the order. Provide the gate-station scheme, drawing revisions, and quantities for each type before production so similar-looking bushings can be identified during assembly.
