Agriculture Gearbox Design and Manufacturing — Rotary Lawn Mower Series

SMI’s engineering team designs and manufactures agricultural gearboxes from initial concept through to finished product — covering 3D CAD design, casting, precision machining and assembly. The rotary lawn mower gearbox series shown on this page represents one area of SMI’s mechanical design and manufacturing capability, with configurations supplied to agricultural equipment manufacturers in Canada and other markets.

All gearbox configurations are developed to customer specification. SMI does not supply standard catalogue products — every configuration is engineered to the specific input/output requirements, mounting geometry and performance specification of the customer’s equipment.

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Design and Manufacturing Capability

In-House CAD Engineering

SMI’s engineering team develops full 3D CAD models of gearbox assemblies before manufacture — covering gear geometry, shaft layout, bearing selection, housing design and assembly clearances. The sectioned CAD model shown above illustrates the multi-stage gear train and internal layout typical of SMI’s rotary mower gearbox designs. In-house design capability means SMI can work from a customer’s functional specification or performance requirement, not just from a finished drawing.

Casting and Housing Manufacture

Gearbox housings are manufactured in-house from aluminium alloy castings — as shown in the production image above. Casting in-house gives SMI direct control over dimensional accuracy, wall thickness consistency and surface finish quality, which are critical to gear alignment and bearing life in the finished assembly.

Precision Machining and Assembly

Machined bores, bearing seats, shaft features and mounting faces are produced to the tolerances required for correct gear mesh and bearing fit. Final assembly and functional verification are carried out before despatch.

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Rotary Lawn Mower Gearbox Series

The series shown covers a range of input power classes — from the 30–40 hp range through to the 70–80 hp range — in multiple mounting and shaft configurations. Standard configurations include horizontal shaft, vertical shaft and right-angle drive layouts to suit different mower deck and PTO connection geometries.

Series	Power Range	Typical Application
30-40 Series	30–40 hp	Mid-range rotary mowers — multiple shaft configurations
50-60 Series	50–60 hp	Heavy-duty rotary mowers — right-angle drive configuration
70-80 Series	70–80 hp	High-power rotary mowers — vertical output shaft configuration

Custom configurations outside this range — different power ratings, gear ratios, shaft dimensions, mounting patterns or housing materials — are available on request. SMI will develop a configuration to the customer’s specific equipment requirements.

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Custom and OEM Supply

SMI’s gearbox manufacturing capability is available to agricultural equipment manufacturers requiring:

• Design from specification — SMI engineers develop the gearbox configuration from the customer’s functional and performance requirements
• Design from drawing — SMI manufactures to the customer’s existing engineering drawing or CAD model
• Design improvement — SMI reviews an existing configuration and proposes engineering changes to improve performance, service life or manufacturability
• OEM supply — finished gearboxes supplied under customer branding and packaging
• Custom configurations — power rating, gear ratio, shaft layout, housing material, surface finish and colour to customer specification

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Request a Consultation

To discuss agricultural gearbox design and supply for your equipment, please provide the following at enquiry stage:

• Input power — hp or kW
• Required gear ratio and output shaft speed
• Shaft configuration — input and output orientation
• Mounting geometry — bolt pattern, flange or foot mounting
• Annual volume requirement
• Existing drawing or specification if available

SMI will respond with a written technical assessment. Contact SMI — Agriculture Gearbox Enquiry →