AIR BRAKE CYLINDER FOR JOHN DEERE AL78940

The AL78940 pneumatic brake compressor is designed for John Deere applications, specifically on tractors in the 6000, 7000, and 7010 series. This part number corresponds to a single-cylinder compressor used to supply the air brake system. When replacing this part, identification is based on the part number as well as the connection specifications and stated operating dimensions.

A Compressor Designed for Pneumatic Braking

This model is a pneumatic brake compressor. Its primary function is to supply the air required by the pneumatic brake system. On a tractor or other compatible machine, it is therefore used to supply air to the brake system, not to an air conditioning system.

The documentation also lists it for certain DAF, Deutz, Faun, Goldhofer, and IVECO applications. For John Deere, the detailed applications apply to the models listed under this part number.

Technical Specifications for Verification

Several data points help ensure you are replacing the correct version:

• Operating pressure: 10 bar
• Displacement: 159 cm³
• Type: single-cylinder
• Piston diameter: 75 mm
• Piston stroke: 36 mm
• Cooling: Luft, i.e., air-cooled
• Operating speed: 3,000 (1/min)

These details are particularly useful when there are several similar compressors on the same tractor series. The cooling method, displacement, and single-cylinder configuration help rule out mismatches.

Connections and Comparison Reference Points

Checking the thread specifications is often crucial before placing an order. This part number includes the following connections: M26 x 1.5 for connection thread 0, M26 x 1.5 for connection thread 0, M10 x 1 for connection thread 8.1, and M22 x 1.5 for connection thread 8.2. The crankshaft thread is M18 x 1.5.

For identification, you can also compare the following part numbers: AL78940, RE207012, AL68237, 12188179, AL78940 411 141 000 R, 4111410000, 411141000R, and 4111410007. These part numbers help match an installed part number with a compatible replacement part number.

Choose the Correct Part Number for Your Tractor

Before confirming your order, compare the part number listed on the installed compressor and verify the exact tractor model. For this family of John Deere applications, certain variants are specified with a geographic designation such as “Europe” or “USA.” This distinction must be taken into account when selecting the part.

If you need a part for a John Deere tractor from the listed series, the best approach is to cross-reference the exact model, part number, and connection threads. This helps rule out a similar model that might not have the same connections or compressor configuration.

If in doubt, note the markings on the part being removed and compare them point by point with this part number before replacement.

Compatibility by Brand and Series

John Deere · 6000 Series

• 6100
• 6100SE
• 6200 (Europe)
• 6200SE
• 6300 (Europe)
• 6300SE
• 6400 (Europe)
• 6400SE
• 6506
• 6600
• 6800
• 6900

John Deere · 7000 Series

• 7600
• 7700
• 7800

John Deere · 7010 Series

• 7610
• 7710
• 7810 (USA)
• Original Part Numbers
• AL78940+RE207012

Deutz / John Deere

• Type
• Single-cylinder
• Piston diameter (mm)
• 75
• Piston stroke (mm)
• 36
• Coolant
• Air
• Additional Information

Deutz / John Deere · Operating speed

• 3000 (rpm)
• Connection thread 0: M26 x 1.5
• Connection thread 2: M26 x 1.5
• Connection thread 8.1: M10 x 1
• Connection thread 8.2: M22 x 1.5
• AL68237
• AL78940 411 141 000 R
• 4111410000
• 411141000R
• 4111410007
• AL78940

FAQ — Frequently Asked Questions

What is the AL78940 compressor used for on a tractor?

This compressor powers the air brake system. It is used to generate the air needed to operate the air brake system, not the air conditioning system. On this model, the rated operating pressure is 10 bar, and it features a single-cylinder design.

How can I identify the correct compressor before replacement?

The surest way is to cross-reference the part number on the removed part with the following part numbers: AL78940, RE207012, AL68237, 12188179, 4111410000, 411141000R, or 4111410007. Also check the M26 x 1.5, M10 x 1, and M22 x 1.5 connections, as well as the M18 x crankshaft thread 1.5.

Is this compressor compatible with the John Deere 6100, 6200SE, 7700, and 7810 (USA) models?

Yes, these models are among the John Deere applications listed for this part number. However, you must ensure that the specific model variants are correct—especially when a model is identified by a geographic suffix such as “Europe” or “USA”—and then compare it to the part number installed on your tractor.

What does the “Luft” cooling designation mean for this part number?

The “Luft” designation indicates air cooling. This is a useful way to distinguish this version from other compressors that may use a different cooling method. When checking, also verify the displacement of 159 cm³ and the 75 mm piston with a stroke of 36 mm.

The original replacement part numbers and brands are provided for comparison purposes only. This does not imply that these are original parts.