Girth Gear Replacement Lead Time: How to Plan Manufacturing, Delivery, and Shutdown

The plant has a shutdown date. The old girth gear may last until then, but nobody wants to test that assumption for longer than necessary. Procurement asks suppliers for the fastest delivery they can offer.

That is a reasonable start. It is not yet a replacement plan.

A girth gear can be finished at the factory and still miss the shutdown. The drawing may be awaiting approval. An inspection witness point may not have been scheduled. The gear may arrive at port but not at the plant. Or the lifting equipment booked for the outage may be unsuitable for the packed segments.

The useful schedule is not “weeks to manufacture.” It is the time from confirmed technical requirements to a gear that is inspected, delivered, and ready to install.

This guide explains what usually controls that schedule for ball mills, rotary kilns, SAG mills, and other large open-gear drives. It also shows which decisions buyers can make early to avoid losing time later.

Ask What the Quoted Lead Time Starts From

A supplier may quote a manufacturing lead time, but the starting point is not always the day you send an inquiry or place an order.

Before comparing quotations, ask each supplier:

• Does the schedule begin after purchase-order receipt?

• After drawing approval?

• After a deposit or other commercial condition is met?

• After material specifications and inspection requirements are agreed?

• Is export packing included in the quoted period?

• Is the quoted date ready for inspection, ready for shipment, or delivery to site?

Two quotations can show the same number of weeks and mean very different things.

Request a schedule with dated milestones rather than a single delivery statement. It should show what the supplier needs from your team and when.

Where the Time Goes

The production route depends on gear size, design, material, and the supplier's manufacturing plan. A large segmented cast-steel gear may move through engineering review, material procurement, casting, heat treatment, machining, tooth cutting, inspection, trial assembly if required, and export packing.

Not every project follows precisely the same sequence. Some work can overlap; other steps cannot begin until an earlier result has been accepted.

The schedule becomes more reliable when each stage has an owner and a defined completion point.

Drawing Approval Is Often the First Schedule Risk

A complete, approved drawing allows the manufacturer to plan against fixed requirements. An incomplete drawing leaves important work open.

Delays commonly arise when:

• The gear drawing and the installed mounting interface do not agree

• The pinion drawing is missing

• The number or arrangement of segments is uncertain

• A material substitution is proposed but not approved

• Tooth data must be reconstructed from a worn gear

• Several drawing revisions are circulating at once

If the original drawing is unavailable, allow time for field measurement and technical review. That work should be treated as part of the project schedule, not squeezed into a manufacturing lead-time estimate.

Nominate one person or team to approve drawing revisions. A supplier cannot reliably hold a production schedule if design decisions remain open after manufacture has begun.

Inspection Can Affect the Critical Path

Buyers rightly ask for material records, dimensional reports, and non-destructive testing. Trouble starts when the inspection scope is defined only after the gear is nearly finished.

Agree on an inspection and test plan before production. Identify:

• Required tests and reports

• Applicable acceptance criteria

• Buyer review points

• Third-party witness or hold points

• Who can approve a deviation

• How quickly the buyer will respond to submitted records

If a third-party inspector must witness a particular stage, arrange availability in advance. Missing a hold point can be difficult or impossible to correct after the operation is complete.

The buyer's own review time matters too. A report waiting several days for approval can delay shipment even when the gear itself is ready.

Decide What Happens to the Pinion Before Ordering

If the existing pinion will be reused, inspect it early. Do not leave the decision until the old girth gear is removed.

The pinion may have substantial wear, pitting, or tooth damage. Its bearings or support may also need attention. Discovering this during the shutdown can change the project from a gear-only installation to a larger drive repair with no replacement pinion available.

For the schedule, make one of three decisions:

1. Reuse the pinion, subject to documented inspection results.

2. Order a new pinion with the girth gear.

3. Keep the decision open, but establish a date by which inspection must resolve it.

The third option is sometimes necessary. It should have a deadline, not remain an unrecorded assumption.

Yile Machinery manufactures custom girth gears and pinions for heavy-duty equipment. If both components may be needed, include both in the initial inquiry so their technical requirements and delivery schedules can be reviewed together.

Do Not Confuse Shipment With Arrival at Site

“Ready for shipment” is not the date a maintenance team can begin installation.

For an export order, clarify the full route:

• Factory completion and release

• Packing

• Inland movement

• Export handling

• Ocean or other freight

• Import clearance

• Delivery from port to plant

• Receipt inspection and storage

Large gear segments may require particular handling, lifting, or transport arrangements. Confirm packed dimensions and weights early enough for the logistics team to plan the route to site.

The purchase agreement should state the applicable delivery terms and destination. It should also make clear who arranges each part of the journey. Avoid assuming that “delivery in eight weeks,” for example, means arrival at the mill when the quotation actually refers to readiness at the supplier's facility.

Work backward from the date the installation crew needs the gear at site, not from the intended factory completion date.

Prepare the Site While the Gear Is Being Made

Manufacturing time can be used well—or lost. While the replacement gear is in production, the plant can prepare the work that does not depend on its physical arrival.

Review:

• The condition of the mounting surface

• Fasteners, locating parts, and any parts due for replacement

• Lifting plans and equipment capacity

• Access for removing the old gear

• Segment handling and laydown space

• Pinion and bearing inspection scope

• Alignment tools and measurement procedures

• Lubrication-system condition

• Storage conditions if the gear arrives before the outage

Check the installation sequence with the site team or appointed contractor. If an old segment must be removed to verify a critical dimension, decide when that verification can safely happen and what it could change in the new gear's specification.

A replacement gear arriving early is helpful only if it remains protected, identifiable, and ready to install.

Build a Schedule With Decision Gates

A practical replacement schedule does not need to be complicated. It does need to show where work must stop until an important decision is made.

Gate 1: Technical Basis Confirmed

The buyer and supplier agree on the drawing, pinion strategy, material, and any dimensions requiring field confirmation.

Gate 2: Inspection Plan Approved

Required tests, acceptance criteria, reports, and witness points are agreed before the relevant manufacturing stages.

Gate 3: Manufacturing Progress Reviewed

The supplier confirms progress against the agreed milestones and identifies any issue that may affect completion.

Gate 4: Factory Release

Required inspection records are reviewed, outstanding deviations are resolved, and the gear is approved for packing and shipment.

Gate 5: Site Readiness

The gear is received and checked, and the plant confirms that parts, lifting equipment, personnel, and installation procedures are ready.

These gates make schedule problems visible while there is still time to respond.

What If the Existing Gear Is Failing Faster Than Expected?

When cracks, broken teeth, or rapidly worsening damage appear, the project may change from a planned replacement to a production-risk decision.

The plant should separate two questions:

• Can the current drive continue operating safely?

• How quickly can a suitable replacement be manufactured and installed?

The first requires assessment by the plant's responsible engineers and maintenance team under its operating procedures. A supplier's earliest possible delivery date is not a basis for declaring a damaged drive safe to run.

For the replacement inquiry, explain the urgency and provide the available drawings, photos, damage description, and required date. Ask which proposed steps affect delivery and whether any requirements remain unresolved. Do not remove essential engineering or inspection checks from the order without understanding the risk.

Information That Helps a Supplier Give a Useful Schedule

A realistic schedule depends on a defined scope. Include the following with your RFQ:

• Equipment type and application

• Approved gear drawing, if available

• Module or diametral pitch, tooth count, diameter, and face width

• Number of segments and mounting details

• Material and heat-treatment requirements

• Pinion drawing or condition report

• Inspection and documentation requirements

• Whether factory trial assembly is required

• Packed-delivery destination

• Required arrival-at-site date

• Planned shutdown and installation dates

• Any critical dimensions still awaiting field verification

If information is missing, say so. A supplier can then distinguish between an indicative schedule and a committed schedule based on approved requirements.

Questions to Ask Before Accepting a Delivery Promise

Use these questions when comparing suppliers:

1. What event starts the quoted lead time?

2. What is included before the gear is declared ready for shipment?

3. Which drawing and specification are the schedule based on?

4. Are inspection and third-party witness points included?

5. What is the proposed milestone schedule?

6. Which buyer approvals could delay the critical path?

7. What are the packed dimensions and weights?

8. Where, exactly, does the quoted delivery obligation end?

9. What changes would require a revised schedule?

The answers are more useful than an unusually short lead time without a defined scope.

Frequently Asked Questions

How long does it take to manufacture a replacement girth gear?

There is no reliable single lead time for every gear. Size, material, segment design, drawing completeness, manufacturing route, inspection requirements, and factory capacity all affect the schedule. Ask for project milestones tied to an approved drawing and inspection plan.

Does the quoted lead time usually include shipping?

Not necessarily. Confirm whether the quotation refers to factory completion, readiness for shipment, arrival at port, or delivery to the plant. The agreed delivery terms should make the supplier's responsibility clear.

Can we place the order before all dimensions are confirmed?

You can begin commercial and technical discussions, but manufacturing critical features from unverified dimensions creates fit and schedule risk. Agree which details must be confirmed before the relevant production work is released.

Will third-party inspection delay the order?

It can if witness points and inspector availability are arranged late. When they are included in the original inspection plan and schedule, they are easier to manage.

Should we order the pinion at the same time?

Inspect the existing pinion before deciding. If it is unsuitable for reuse, ordering it later may put the shutdown at risk. If its condition is uncertain, request an alternative quotation and set a deadline for the decision.

What is the most important date to give the supplier?

Give both the required arrival-at-site date and the planned shutdown date. Also explain how much time the plant needs for receipt inspection and preparation before installation begins.

Plan Backward From Installation

The best replacement schedule starts at the machine, not at the factory gate. Establish when the site needs the gear, work backward through transport and inspection, and settle the technical details early enough to protect the manufacturing window.

If you are planning a girth gear replacement, send Yile Machinery your drawing or available measurements, equipment details, inspection requirements, destination, and shutdown dates. We can review the scope for your girth gear and pinion project and identify the information needed to prepare a project-specific quotation and schedule.

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