Gearbox for Disc Mower

Compatible models: Model 2874, Mk-II, Type 54L. Direct bolt-on replacement — no modifications required.

Compatible models: G7.3, H-917, Model 9166. Direct bolt-on replacement — no modifications required.

Compatible models: Series 850, Type 90F, 227R. Direct bolt-on replacement — no modifications required.

Compatible models: C-835, Mk-III, Type 27C. Direct bolt-on replacement — no modifications required.

Compatible models: F-164, Mk-V, G7.3. Direct bolt-on replacement — no modifications required.

Compatible models: 974S, G3.5, Mk-II. Direct bolt-on replacement — no modifications required.

Bearing kits (input & output), seal kits (all positions), matched gear pairs, shaft assemblies, overhaul kits, hardware packs. All ship within 24-48 hours.

How: Record the brand, model number, and any part numbers from the nameplate of the gearbox being replaced

Why it matters: Speeds up the matching process and ensures dimensional compatibility with your hay cutting implement

How: Refer to your disc mower manufacturer’s manual for the recommended disc drive train operating speed

Why it matters: Together with PTO speed, this defines the exact gear ratio your gearbox needs

How: Estimate your annual operating hours for the disc mower to determine appropriate service life rating

Why it matters: High-hour operations justify premium bearing and gear specifications for lowest cost per hour

How: Match the gearbox HP rating to your tractor’s PTO horsepower output and the disc mower’s demand

Why it matters: Under-rating leads to overheating and premature failure; over-rating adds unnecessary cost and weight

How: Assess exposure to dust, moisture, chemicals, and temperature extremes in your typical hay cutting conditions

Why it matters: Determines the appropriate seal grade, surface coating, and housing material specification

How: Check your tractor’s PTO specification — standard is 540 RPM or 1000 RPM

Why it matters: Determines the input shaft spline size and the baseline for ratio calculation

How: Measure the bolt hole positions, centre distances, and overall envelope on your disc mower’s gearbox mounting flange

Why it matters: Ensures direct bolt-on installation without any fabrication or adapter plates

Disconnect the PTO driveline from the gearbox input shaft. Support the gearbox weight with a floor jack or overhead hoist (typical weight: 15-70 kg depending on model). Remove all mounting bolts in a criss-cross pattern to relieve clamping stress evenly. Carefully lower the old gearbox and set it aside.

Locate the drain plug on the existing gearbox and position a catch container underneath. Remove the drain plug and allow all oil to drain completely — inspect the oil for metal particles or discolouration that may indicate internal wear. Record the old gearbox model number, mounting bolt size, and shaft dimensions for reference.

Attach the gearbox output shaft to the disc mower’s disc drive train drive coupling. For keyed connections, align the keyway and slide the coupling on, then secure with the retaining bolt and torque to specification. For splined outputs, apply anti-seize to the splines and verify full engagement before locking.

Clean the mounting flange on the disc mower frame with a wire brush and solvent, removing all old sealant, rust, and debris. Inspect the mounting surface for cracks, stripped threads, or warping. Chase any damaged bolt threads with a tap. Apply a thin film of anti-seize compound to the mounting face if specified.

Remove the fill plug and slowly add the recommended gear oil until it reaches the level indicator. Use the lubricant grade specified in the gearbox documentation (typically SAE 80W-90 GL-5 or equivalent). Replace the fill plug and hand-tighten, then snug with a wrench. Verify the breather cap is clean and unobstructed.

Align the PTO driveline with the gearbox input shaft and slide the yoke onto the splines until the locking mechanism engages. Verify the spline count matches (6-spline for 540 RPM, 21-spline for 1000 RPM). Check that driveline operating angles do not exceed 15° — excessive angles cause premature U-joint failure and vibration.

Park the tractor on firm, level ground. Engage the parking brake and place wheel chocks. Turn off the engine and remove the key. Disconnect the PTO shaft from the disc mower. Allow all components to cool completely before touching. Wear appropriate PPE including gloves and safety glasses.

Start the tractor and engage the PTO at low RPM (approximately 300 RPM). Listen carefully for any grinding, whining, knocking, or clicking sounds. Run at low speed for 15-20 minutes, monitoring the gearbox housing temperature by hand (carefully). Check for oil leaks at all seals and the mounting interface. Gradually increase to full operating speed.

Probable Cause: Insufficient lubricant or incorrect oil grade

Recommended Action: Drain and inspect oil for metal particles. Refill with correct grade. If noise persists after oil change, bearing or gear inspection is required. Contact support for rebuild guidance.

Probable Cause: Operating beyond rated horsepower or duty cycle

Recommended Action: Check oil level and grade against the specification. Clean all debris from the housing exterior — especially the cooling fins. If the disc mower is being operated at or above the gearbox’s rated power, reduce forward speed or PTO load. Consider upgrading to synthetic gear oil for improved thermal performance.

Probable Cause: Rust or debris on the input shaft splines

Recommended Action: Clean the input shaft splines with a wire brush and apply a light coat of anti-seize. Slowly rotate the PTO shaft while pushing to align the splines. If the splines will not engage, verify the spline count matches your PTO standard — 6-spline for 540 RPM, 21-spline for 1000 RPM.

Probable Cause: Stripped gear teeth or broken gear

Recommended Action: Check the overload protection device first — this is the most likely cause if the gearbox was recently subjected to a sudden overload. Replace the shear bolt or reset the slip clutch per the manual. If overload protection is intact, the gearbox has internal damage and requires professional service.

Probable Cause: Loose internal components or retaining hardware

Recommended Action: A clunking sound specifically on PTO engagement (but not during operation) usually indicates driveline lash — check driveline telescoping tube for wear. If the clunk occurs during operation, it may indicate excessive gear backlash from internal wear. Have the gearbox inspected if the sound is progressive.

Our gearbox matches or exceeds OEM specifications across all measurable parameters. Key improvements include upgraded bearing classes, superior seal materials, enhanced heat dissipation, and the option for custom gear ratios that OEM catalogues do not offer. The result is a drop-in replacement that typically outlasts the original.

We offer a comprehensive range of ratios from 1:1 through 1:6 to match virtually any disc mower configuration. Standard catalogue ratios ship within days; custom ratios can be manufactured within 2-3 weeks. Our engineers will recommend the optimal ratio based on your tractor PTO speed and hay cutting requirements.

We maintain compatibility databases covering disc mower models from the past 25+ years. Most older models can be directly fitted with our current gearbox range. For discontinued or rare models, send us the mounting dimensions and shaft specifications, and we will confirm fitment or design a custom adapter.

We accept bank transfer, credit card, and purchase orders from established accounts. For large orders, we offer 30-day payment terms subject to credit approval. Orders can be placed through our website, by email, or by phone. Pro-forma invoices are available for pre-payment arrangements.

If you provide your equipment details before ordering and we confirm compatibility, fitment is guaranteed. In the rare event of a compatibility issue, we offer a no-questions-asked exchange or refund on unused gearboxes within 30 days of delivery. Our goal is to match you with the correct gearbox on the first order.

Yes — we ship to every postcode in Australia, including remote and regional areas. We use experienced agricultural freight carriers who understand the urgency of seasonal equipment needs. Express shipping is available for emergency breakdown situations, and we maintain stock for immediate dispatch of popular models.

Provide us with your tractor brand/model and PTO speed, the disc mower manufacturer and model, and the old gearbox part number if available. Alternatively, measure the input/output shaft dimensions and mounting bolt pattern. Our selection engineers will identify the correct match, typically within 24 hours.

The gearbox is specifically designed for the dynamic and impact loading characteristic of hay cutting applications. Case-hardened alloy steel gears absorb repetitive shocks, while the optional overload protection (shear bolt or slip clutch) safeguards against catastrophic overload events. The bearing selection and housing rigidity are both matched to disc mower load profiles.

Our 24-month comprehensive warranty covers all defects in materials and workmanship, including bearings, gears, seals, and housing. It applies from the date of purchase and is backed by our ISO-certified quality management system. Extended warranty programs are available for bulk and fleet orders.

Routine service (oil changes, seal replacement, bearing inspection) can be performed on-site with standard tools. For major rebuilds, we supply complete overhaul kits containing all bearings, seals, and gaskets. Detailed service manuals and video guides are available for download from our support portal.

Gearbox housings safely contain internal operating pressures in compliance with applicable standards.

Gearbox design follows the general principles of risk assessment and risk reduction for hay cutting equipment.

All gears rated and verified per international standards for tooth root fatigue and surface durability.

specifies risk assessment requirements for hay cutting machinery operations.

mirrors national standards for agricultural machinery including disc mower equipment.

mandates operator training for all PTO-driven disc mower equipment.