What's the difference between bevel and parallel-shaft gearboxes?
A bevel gearbox changes shaft direction (typically 90 degrees) using conical gear teeth — the dominant configuration on Australian agricultural implements because PTO input is horizontal but most working components run vertically or transverse. A parallel-shaft gearbox keeps input and output axes parallel, using helical or spur gears, and is mainly used where speed change is needed without direction change (drum mower internal stages, some tiller second stages). For 80 percent of Australian implement applications, bevel is the right answer.
What ratio do I need for a slasher or rotary cutter?
For most slashers running standard 540 RPM input, the common ratios are 1:1 (output equals input), 1:1.46 (output around 790 RPM), and 1:1.93 (output around 1,040 RPM). Higher ratios produce higher tip speed for cleaner cutting in heavy growth — 1:1.93 is typical for 5-foot to 7-foot slashers in dense grass. Lighter slashers and post-hole-digger-style cutters often use 1:1 to maximise low-end torque. Match the ratio to the original equipment specification or to the implement working speed marked on the data plate.
How do I calculate the right service factor?
Service factor multiplies nominal tractor PTO power by an industry-standard coefficient that accounts for shock loading and duty cycle. Steady-load light duty (irrigation, light slashers in clean pasture): 1.0 to 1.25. Moderate shock (rotary cutters, tillers in normal soils): 1.5 to 1.75. Heavy shock (slashers in stumpy bush, balers in wet hay, augers in stones): 2.0 to 2.5. Severe shock (forage harvesters, sugar cane choppers, stalk shredders): 2.75 to 3.0. Multiply tractor PTO kW by the factor and choose a gearbox rated above that figure.
Cast iron or aluminium housing — which should I choose?
Cast iron for any shock-loaded application — slashers, rotary cutters, tillers, balers, augers. The mass and rigidity maintain bevel gear meshing under deflection and absorb impact loads. Aluminium is acceptable only for steady-load light duty — small mowers, light irrigation pumps, lightweight rakes. Aluminium housings flex too much under shock loading and the bevel gears wear out 2 to 3 times faster than in cast iron. The weight saving on a tractor implement is rarely worth the durability penalty.
Can your gearboxes replace units from major OEM brands?
Yes — we manufacture to a large library of OEM patterns and can reverse-engineer gearboxes from a worn sample. Provide the OEM part number stamped on the housing, a photo of the gearbox from the side and the mounting flange, or your implement model and serial number. We confirm interchangeability before quoting. Direct dimensional matching is standard; for high-duty applications we also offer material upgrades over the original specification (cast iron upgrade from aluminium, hardened gear teeth where original was un-hardened).
Can you make a gearbox to a custom ratio?
Yes — about 15 percent of our output uses custom ratios outside the standard catalogue. Custom ratios typically arise for specialty implements (specific pump speeds, unusual blade-tip targets, OEM equipment ratios that don't match catalogue values). Provide the input RPM, required output RPM, transmitted power, mounting envelope and shaft sizes — our engineers translate that into a viable gear set and confirm the ratio is achievable in the available envelope. Lead times for custom ratios are slightly longer than catalogue items.
What oil should I use, and how often do I change it?
Most agricultural gearboxes ship from the factory filled with EP90 (mineral) or EP140 (heavier mineral) extreme-pressure gear oil. EP90 suits cooler climates and lighter duty; EP140 is the better choice for hot Australian summers and shock-loaded duty. Run-in change at 50 hours, then full change every 250 hours of running or once per season — whichever comes first. Synthetic 80W-140 is an upgrade option for severe-duty applications and extends change intervals to around 500 hours. Always check the seal-side oil level monthly during the working season.
Do you provide ISO certificates and inspection reports?
Yes — every shipment ships with a certificate of conformity referencing our ISO 9001 quality system. Material chemistry certificates, gear tooth hardness reports, dimensional inspection reports against drawing tolerances and seal pressure-test data are all available on request. For OEM customers we provide serialised lot traceability so any future warranty issue can be traced to the specific manufacturing batch.
What warranty applies to your agricultural gearboxes?
All gearboxes carry a 12-month manufacturing defect warranty from date of dispatch, covering material flaws, dimensional non-conformance, premature gear or bearing failure under rated load, seal defects and heat-treatment defects. Wear from normal field use is not covered, nor is damage caused by under-sized gearbox selection, missing oil, missing or incorrectly torqued mounting bolts, or operation outside rated input speed. Where a warranty claim is approved, the worn gearbox is requested for return inspection and a replacement ships at our cost.