Powertrain & Gear Testing

FZG gear test rig

Overview

The FZG gear test rig (Forschungsstelle für Zahnräder und Getriebebau – Gear Research Centre, Technical University of Munich) is the globally recognized back-to-back power circulation test machine for evaluating gear lubricants and determining load carrying capacity according to international standards. With standardized test procedures referenced in ISO, ASTM, DIN, CEC, and API specifications, FZG test results are directly comparable across laboratories worldwide and accepted by OEMs and lubricant manufacturers.

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Schematic of a standard FZG gear test rig.

Availability

Features and specifications

The closed-loop power circuit design connects a drive gearbox and test gearbox through torsionally preloaded shafts. A clutch mechanism on one shaft allows precise load application via weight system, tension ratchet, or automatic clamping. This configuration enables high-load testing (up to 800 Nm) with minimal drive motor power consumption, as the motor only compensates for friction losses in the system.

Standard FZG-A test gears feature a 16-tooth pinion meshing with a 24-tooth wheel (module 4.5 mm, 20° pressure angle, 20 mm face width) at 91.5 mm center distance. The characteristic values obtained—scuffing load stage, pitting life, micropitting rating, and wear mass loss—can be used directly for gear rating calculations according to ISO 6336.

Gear testing capabilities

Testing of spur and helical gears (FZG-A, C, PT types)
Torque capacity up to 800 Nm
Variable speed range: 100–3000 rpm
Bidirectional rotation (forward and reverse testing)
Standard 91.5 mm center distance
Low-speed operation: 4 rpm with optional reduction gear

Lubricant characterization

Scuffing load capacity (failure load stage 1–12+)
Pitting durability testing (up to 300 hours)
Micropitting (grey staining) performance rating
Wear mass loss measurement at defined intervals
EP additive performance evaluation
Results directly usable for ISO 6336 gear rating

Lubrication system

Oil bath (dip) lubrication up to 120°C
Oil jet (injection) lubrication up to 90°C
Precise temperature control (±2°C accuracy)
Two independent oil circulation units available
Compatible with mineral, synthetic, and bio-based oils
ATF, MTF, and industrial gear oils supported

Load application methods

Weight system (dead weights) for 12 load stages
Tension ratchet for precise manual loading
Automatic hydraulic clamping system (optional)
Constant load and step load operation modes
Shock load testing capability (S-A10/16.6R/90)

Control and software

Windows 7 / 10 / 11 compatible software
Real-time torque, speed, temperature display
Automated test sequence execution
Pre-programmed standard test procedures
Data logging with CSV/Excel export

Safety and handling

Enclosed housing with safety interlocks
Emergency stop functionality
CE marked and compliant

Included accessories

Complete tool set for gear changeover
Gear mounting and alignment fixtures
Standard FZG-A test gear set (1 pair)
Calibration weights for load stages
Oil sampling equipment
Operation and maintenance manuals

Available upgrades

Torque measurement in power loop – inline transducer for real-time transmitted torque monitoring
Load spectra module – programmable variable load profiles for duty cycle simulation
Efficiency module – precision power measurement for gear mesh efficiency calculations
Spray lubrication unit – directed oil jet system with adjustable flow rate and nozzle positioning

Specifications

Parameter	Specification
Gear types	Spur and helical gears (FZG-A, C, PT)
Maximum torque	800 Nm
Speed range	100–3000 rpm
Pitch line velocity (standard test)	8.3 m/s at 1450 rpm
Rotation direction	Bidirectional
Center distance	91.5 mm
Test gear module	4.5 mm (standard FZG-A)
Test gear tooth numbers	Pinion: 16T / Wheel: 24T
Test gear face width	20 mm (A-type) / 10 mm (A10-type)
Oil temperature – bath lubrication	Ambient to 120°C (±2°C)
Oil temperature – jet lubrication	Ambient to 90°C (±2°C)
Load application	Weight system / ratchet / auto clamping
Control system	Siemens PLC with HMI touchscreen
Software compatibility	Windows 7 / 10 / 11
Power supply	400V 3-phase, 50/60 Hz

Standards

Applicable testing standards

ISO 14635-1

FZG scuffing test A/8.3/90

ASTM D5182

Scuffing load capacity (visual)

CEC L-07-95

Load carrying capacity test

CEC L-84-02

Step load test (high EP)

DIN 51354

German FZG standard

ASTM D4998

Gear wear evaluation

Custom

OEM-specific procedures

Standard FZG-A Test Gear Specifications

Parameter	Pinion	Wheel
Number of teeth	16	24
Normal module	4.5 mm
Normal pressure angle	20°
Helix angle	0° (spur)
Face width	20 mm
Profile shift coefficient	+0.8635	−0.5103
Tip diameter	88.7 mm	112.5 mm
Material	20MnCr5 (case-hardened)
Surface roughness Ra	0.35 ± 0.1 µm	0.30 ± 0.1 µm

Test gears are consumable items. Replacement gear sets (FZG-A, FZG-C, FZG-PT) available for order separately. Contact us for current pricing and lead times.