DI-SAN DS321 Corn Header Gearbox: Specifications and Selection

A corn header driveline must transfer power reliably while maintaining the rotational speed required by the machine’s working mechanisms. The gearbox performs a key role in this system: it changes the rotational speed and directs power to the corresponding header drive.

The DI-SAN DS321 is a speed-increasing agricultural gearbox designed for corn headers. It operates at an input speed of 1,000 rpm and increases the output speed to 2,077 rpm. The model is rated for an input power of 15 hp, or 11 kW.

Application of the DI-SAN DS321 Gearbox

DI-SAN specifies the DS321 for use in corn headers. The gearbox is installed as part of the header driveline and provides the speed ratio required by the machine design.

The DS321 should not be selected solely by its general application or the appearance of its housing. Corn headers can use several gearboxes with different ratios, shaft arrangements, rotation directions and mounting dimensions.

The DI-SAN range also includes the DS320, DS322 and DS323 corn header gearboxes. Although these models belong to the same equipment category, they are not automatically interchangeable. Each gearbox must be selected according to the specifications and installation geometry of the particular header.

How the DS321 Changes Rotational Speed

The DS321 has a gear ratio of 1:2.07. This means that the output shaft rotates faster than the input shaft.

At an input speed of 1,000 rpm, the manufacturer specifies an output speed of 2,077 rpm. The DS321 is therefore a speed-increasing gearbox rather than a reduction unit.

A calculation based on the published ratio of 1:2.07 gives approximately 2,070 rpm. The small difference from the specified 2,077 rpm is explained by rounding of the published gear ratio.

It is important to distinguish between gearbox shaft speed and the speed of a particular header mechanism. The stated 2,077 rpm applies to the gearbox output shaft. If the driveline contains an additional chain, belt or gear stage, the final speed of the working mechanism will be different.

DI-SAN DS321 Technical Specifications

These specifications describe the operating parameters of the gearbox itself. The 15 hp or 11 kW rating should not be interpreted as the total power requirement of the corn header or the power output of the combine harvester.

Power and Output Torque

The rated input power of the DS321 is 11 kW, while the specified output torque is 49 Nm.

At an output speed of 2,077 rpm, a torque of 49 Nm corresponds to an output power of approximately 10.7 kW. This value is consistent with the stated input power when rounding and normal mechanical losses in the transmission are taken into account.

The relationship between speed and torque is important when selecting a replacement gearbox. A model with a different ratio can produce an unsuitable output speed even if its power rating and external dimensions appear similar.

Installing a gearbox with the wrong ratio may change the operating speed of the driven mechanism, increase dynamic loads and disrupt the intended operating mode of the header.

What the Input Speed Means

The specified input speed of 1,000 rpm refers to the input shaft of the DS321 gearbox. It does not necessarily mean that the gearbox is connected directly to a tractor or combine PTO shaft.

A corn header driveline may contain intermediate shafts, chain drives, belt drives or other transmission stages. These components establish the speed delivered to the gearbox input.

For correct selection, the actual speed at the DS321 input shaft must therefore be verified rather than assumed from the nominal PTO speed of the power unit.

How to Select a DS321 Replacement Gearbox

Before ordering a replacement gearbox, the following parameters should be checked:

1. The manufacturer and exact model of the corn header.
2. The designation marked on the original gearbox.
3. The gearbox installation position.
4. The required input speed.
5. The required output speed.
6. The gear ratio.
7. The permissible power and torque.
8. The direction of rotation of the input and output shafts.
9. The shaft configuration and spline dimensions.
10. The housing and mounting dimensions.
11. The position and spacing of the mounting holes.
12. The arrangement of the adjacent driveline components.

Matching the designation of the original unit remains the most reliable identification method. If the marking cannot be read, the gearbox must be compared using its dimensions, shaft configuration, mounting points and operating parameters.

External similarity alone is insufficient. Two gearboxes can have similar housings while differing in internal ratio, shaft design or direction of rotation.

Installation and Initial Inspection

Before installation, the gearbox housing, shafts, splines and mounting surfaces should be inspected for damage. The mating shafts and driveline components must align correctly without forcing the gearbox into position.

During installation, it is important to verify:

• correct alignment of the connected shafts;
• secure mounting of the housing;
• proper engagement of spline connections;
• unrestricted shaft rotation;
• absence of excessive radial or axial play;
• correct direction of rotation;
• appropriate oil level before operation.

Misalignment creates additional loads on the bearings and shafts. Loose mounting connections can cause vibration and damage the gearbox housing or adjacent header components.

After installation, the driveline should first be operated without maximum load. The gearbox must run smoothly, without abnormal noise, excessive vibration or oil leakage.

Lubrication and Maintenance

DI-SAN specifies SAE 90 or SAE 140 oil for the DS321. The nominal oil capacity is 0.70 litres.

The oil level and condition should be checked regularly. The housing and shaft seals must also be inspected for leakage. Oil loss reduces lubrication of the gears and bearings, increasing operating temperature and accelerating wear.

Maintenance should include inspection of:

• the oil level and condition;
• the housing and seals;
• the input and output shafts;
• radial and axial shaft play;
• mounting bolts;
• connected shafts and couplings;
• driveline alignment;
• unusual noise or vibration during operation.

The oil-change interval and lubricant selection should also comply with the maintenance instructions for the specific corn header on which the gearbox is installed.

Causes of Premature Gearbox Wear

The service life of a corn header gearbox depends on correct selection, installation and driveline condition. Premature wear can be caused by:

• operation with insufficient oil;
• oil leakage through worn seals;
• incorrect shaft alignment;
• loose gearbox mounting;
• excessive input speed;
• shock loads in the driveline;
• worn or damaged spline connections;
• excessive radial or axial shaft loads;
• operation with worn bearings;
• installation of a gearbox with an unsuitable ratio.

Noise, vibration, increasing shaft play, oil leakage and excessive housing temperature are signs that require inspection. Continued operation under these conditions may damage the gears, bearings, shafts and connected header mechanisms.

DI-SAN DS321 Corn Header Gearbox from BAS-Agro

BAS-Agro supplies DI-SAN agricultural gearboxes and assists customers in selecting units according to their application, gear ratio, shaft arrangement and mounting dimensions.

You can view the specifications and buy the DI-SAN DS321 corn header gearbox on the BAS-Agro website.

For accurate selection, customers should provide the corn header model, the designation of the existing gearbox and photographs of the shafts and mounting points. Key dimensions should also be measured if the original marking is missing or unreadable.

The DI-SAN DS321 is a speed-increasing gearbox designed for corn headers. With an input speed of 1,000 rpm and a gear ratio of 1:2.07, it provides an output speed of 2,077 rpm.

The gearbox is rated for an input power of 15 hp, or 11 kW, and delivers an output torque of 49 Nm. It requires 0.70 litres of SAE 90 or SAE 140 oil and weighs 14 kg.

Correct selection requires more than matching the equipment category. The original gearbox designation, gear ratio, speeds, shaft configuration, rotation direction and mounting dimensions must all correspond to the corn header driveline. This ensures that the DS321 operates within its intended speed and load range.