SAE 7,5
SAE 7.5 / SAE 7 ½ Flywheel Standard – Coupling Fitment Guide
The SAE 7.5 flywheel standard (also written as SAE 7 ½) defines the bolt circle, outer diameter, and bolt pattern for connecting diesel engines with couplings and pump drives. By standardizing these dimensions, engine manufacturers and coupling producers ensure interchangeability, precision alignment, and reliable torque transfer.
SAE 7.5 / SAE 7 ½ Dimensions (Catalogue Reference):
- Outer diameter (Ø): 241.2 mm
- Bolt pattern (Z): 8 × Ø9
- Bolt circle (DO): Ø222.25 mm
Applications in Couplings:
Several OEM coupling solutions are available for engines with an SAE 7.5 flywheel, including:
- KTR BoWex® FLE-PA – torsionally stiff curved-tooth couplings for engine–pump connections.
- KTR BoWex® Elastic – flexible couplings for smoother torque transfer.
- CENTAFLEX-K – elastic couplings developed in close cooperation with leading engine manufacturers.
Why SAE Standards Matter:
SAE standards allow couplings to be installed directly on flywheels from globally recognized engine producers such as Perkins, Hatz, John Deere, Deutz, and Caterpillar. The standardized bolt circle and flange dimensions guarantee correct fit, reducing installation errors and ensuring long service life of both coupling and drive train.
⚠️ Only original OEM couplings (marked with identifiers such as KTR-Kupplungstechnik, BoWex, FLE-PA, >PA6-GF25<, D-4440 Rheine, CENTAFLEX K) ensure that the SAE 7.5 geometry is fully respected. Copies may deviate in bolt alignment or material strength, risking vibration, misalignment, and costly downtime.
