Gearboxes for Rotary Mowers: Features of the DI-SAN DS205 and DS206

A rotary mower-shredder operates under conditions in which its transmission is exposed not only to continuous loads but also to significant impact loads. The blades encounter dense vegetation, dry stalks, branches, stones and other obstacles. Therefore, a gearbox for a rotary mower must provide the required rotor speed, withstand the transmitted torque and remain reliable during prolonged operation.

BAS-Agro is an official supplier of gearboxes manufactured by the Turkish company DI-SAN. The manufacturer’s range for rotary mower-shredders includes the DS205 and DS206 right-angle gearboxes. Both models are designed for an input speed of 540 rpm and a stated input power of 37 kW, but they differ in gear ratio, output speed and torque.

What Machines Are the DS205 and DS206 Designed For?

In the English-language DI-SAN catalogue, the DS205 and DS206 are classified as Rotary Mower gearboxes. The Turkish documentation uses the term Ot Parçalama Makinası, meaning a machine for cutting and shredding grass.

Therefore, these gearboxes are primarily intended for machines with horizontally rotating blades, including:

• rotary mower-shredders;
• rotary cutters;
• orchard mowers;
• grass and vegetation shredders;
• pasture-maintenance machines;
• municipal equipment for cutting overgrowth and maintaining roadsides;
• single-section and multi-section rotary machines.

These machines should not be confused with rotary disc mowers or widely used twin-drum hay mowers. DI-SAN places disc mowers in a separate product category and offers other gearbox models for them. The general type of machine alone is therefore not sufficient to confirm gearbox compatibility.

How a Rotary Mower Gearbox Works

Rotation from the tractor’s power take-off is transmitted through the PTO shaft to the gearbox input. Inside the housing, the right-angle gear train changes the direction of power flow by approximately 90 degrees. Rotation is then transferred to the vertical shaft connected to the rotor or blade carrier.

The DS205 and DS206 are speed-increasing right-angle gearboxes. With an input speed of 540 rpm, they produce a higher speed at the output. The term “gearbox” is therefore more technically accurate than “reduction gearbox,” because these units increase rather than reduce rotational speed.

A single-rotor machine may use one central rotary mower gearbox. Wide multi-section equipment can have a more complex driveline in which a central distribution gearbox transfers power through additional drive shafts to the gearboxes of individual cutting sections.

Technical Specifications of the DI-SAN DS205 and DS206

These specifications have been cross-checked against the manufacturer’s current product pages, the official DI-SAN catalogue and the BAS-Agro product listings.

DI-SAN DS205: Higher Output Speed

The DI-SAN DS205 has a gear ratio of 1:3. With the standard input speed of 540 rpm, it produces an output speed of 1,620 rpm. The stated output torque is 212 Nm.

This transmission arrangement is intended for machines whose working components require a comparatively high rotational speed. Higher speed allows the blades to interact intensively with vegetation. However, cutting and shredding performance depends on more than the gearbox alone. Rotor diameter, blade shape, blade weight, the number of blades, operating height and forward speed are also important.

The DS205 requires 2.50 litres of oil and weighs 31.50 kg. The manufacturer’s drawing shows a right-angle arrangement with a horizontal input and a vertical output shaft.

DI-SAN DS206: Lower Speed and Higher Torque

The DI-SAN DS206 also operates with an input speed of 540 rpm but has a gear ratio of 1:1.69. The manufacturer specifies an output speed of 914 rpm and an output torque of 375 Nm.

Compared with the DS205, this model delivers a lower output speed but substantially higher torque. Such a configuration may be required for machines with a different rotor design, a higher load on the working unit or other driveline requirements.

The DS206 has an oil capacity of 2.25 litres and weighs 28.50 kg. Like the DS205, it is a right-angle gearbox with a vertical output.

A calculation based on the rounded ratio of 1.69 gives approximately 912.6 rpm, whereas the manufacturer specifies 914 rpm. This small difference is explained by the rounding of the published gear ratio and is not a technical inconsistency.

Why the DS205 and DS206 Are Not Interchangeable

Both models have the same input speed and the same stated power rating of 37 kW, or 50 hp. However, this does not make them interchangeable.

The DS205 provides:

• a threefold increase in speed;
• an output speed of 1,620 rpm;
• an output torque of 212 Nm.

The DS206 provides:

• an approximately 1.69-fold increase in speed;
• an output speed of 914 rpm;
• an output torque of 375 Nm.

Installing the higher-speed DS205 in a machine designed for the DS206 could cause the rotor to operate at an excessive speed. The reverse substitution could result in insufficient blade speed and reduced cutting performance. Shaft arrangement, direction of rotation, output-shaft design and mounting dimensions must also be considered.

It is also important to remember that 1,620 and 914 rpm are gearbox output speeds. They should only be described as blade speeds if there is no additional drive stage between the gearbox and the rotor.

How to Select a Gearbox for a Rotary Mower

Selecting a gearbox solely by the appearance of its housing is one of the most common mistakes. Two visually similar gearboxes may have different ratios, shaft configurations and mounting geometry.

Before ordering a replacement, verify:

1. The exact type and model of the mower.
2. The original designation of the existing gearbox.
3. The required input speed.
4. The required output speed.
5. The gear ratio.
6. The permitted power and torque.
7. The direction of shaft rotation.
8. The position of the input and output shafts.
9. The type and dimensions of the spline connection.
10. The design of the vertical output shaft.
11. The mounting-hole spacing.
12. The gearbox installation position on the machine.

The official DS205 and DS206 drawings show a 1⅜-inch, six-spline input connection designated Z6. Nevertheless, the ordered version must be checked against the actual PTO shaft and the technical drawing of the machine.

If the identification plate or original marking is no longer legible, photographs of the gearbox, shafts and mounting points should be provided together with the principal dimensions.

Why a Rotary Mower Gearbox Wears Out

A gearbox for a rotary mower operates under variable loads. During uniform mowing, the transmitted torque remains relatively stable. When a blade strikes an obstacle, however, the load can increase abruptly.

• The principal causes of premature wear include:
• blades striking stones, stumps or metal objects;
• the rotor becoming blocked by dense vegetation;
• engaging the PTO abruptly at high engine speed;
• an incorrectly adjusted or seized slip clutch;
• using an unsuitable shear bolt;
• operating with bent or unevenly weighted blades;
• excessive vibration of the working unit;
• insufficient oil;
• oil loss through damaged seals;
• a blocked or defective breather;
• loose gearbox mounting bolts;
• PTO driveline misalignment;
• operation with worn bearings.

Prolonged operation with excessive vibration is particularly dangerous. Dynamic loads are transferred to the shafts and bearings, impair seal performance and accelerate wear of the gear teeth.

Lubrication and Maintenance

DI-SAN specifies SAE 90 or SAE 140 oil for the DS205 and DS206. The nominal oil capacity is 2.50 litres for the DS205 and 2.25 litres for the DS206.

The publicly available DI-SAN documentation does not specify a universal oil-change interval, an API service classification or the precise temperature ranges for choosing between SAE 90 and SAE 140. Maintenance decisions should therefore also take account of the machine’s operating manual and the supplier’s recommendations.

An API GL-4 or GL-5 classification should not be assigned without confirmation, nor should the specified lubricant be replaced with oil of a different viscosity without checking its suitability.

Before the beginning of the season, the operator should inspect:

• the oil level and condition;
• the housing and seals for leakage;
• the gearbox breather;
• play in the input and output shafts;
• the tightness of mounting connections;
• the condition of the PTO shaft;
• the operation of the protective clutch;
• blade condition and balance.

The PTO should be engaged at a low engine speed, after which the driveline can be brought gradually to the required operating speed. Abrupt engagement creates additional shock loads on the PTO shaft, gearbox shafts, gears and bearings.

During operation, attention should be paid to unusual noise, vibration and excessive housing temperature. These symptoms may indicate insufficient lubrication, bearing damage, incorrect gear engagement or overloading of the working unit.

DI-SAN Rotary Mower Gearboxes from BAS-Agro

BAS-Agro is an official supplier of gearboxes manufactured by the Turkish company DI-SAN. The company can help select a suitable model according to its intended application, gear ratio, shaft configuration and mounting dimensions.

The gearbox section includes models for different types of agricultural and specialised equipment. If the required unit is not currently available, customers can enquire about ordering it. Delivery is available throughout Ukraine.

For accurate identification, customers should provide the machine model, the designation of the original gearbox and photographs of its mounting elements. This approach reduces the risk of ordering an incompatible unit and allows its technical suitability to be checked in advance.

A gearbox for a rotary mower-shredder does more than change the direction of rotation. It also establishes the speed and torque characteristics required by the working unit. The DI-SAN DS205 and DS206 are both designed for a 540 rpm input and a stated input power of 37 kW, but they serve different operating requirements.

The DS205 increases the output speed to 1,620 rpm and provides 212 Nm of torque. The DS206 delivers 914 rpm and a higher torque of 375 Nm. The correct model must therefore be selected according to the specifications of the particular mower, rather than solely by tractor power or housing appearance.

The correct gear ratio, matching installation dimensions, effective PTO protection and regular oil-level inspections directly affect gearbox reliability and the service life of the entire rotary machine.