What it is

Torque sensors Type 4502A are strain gauge based non-contact shaft torque transducers. They are optionally available with an integrated encoder.

The Kistler 4502A Mini-Smart is a compact strain gage torque sensor with a rotating measuring shaft, rated from 4.43 to 8,851 lbf·in (0.5 to 1,000 N·m). Integral electronics transfer the signal without contact and deliver an active ±5 VDC output, electrically isolated from supply and measuring signal. Standardized square, 1/4" hex, and shaft-end connections adapt it quickly to air, electric, and pulse tools.

• Rated torque: 4.43 … 8,851 lbf·in (0.5 … 1,000 N·m)
• Accuracy class: 0.2, linearity incl. hysteresis <±0.2 %FSO
• Smart: integral measuring electronics, active ±5 VDC output
• Non-contact signal transfer: maintenance-free
• Unipolar supply: 11 … 26 VDC, <1 W
• Optional rotational angle measurement: 2 × 360 pulses/rev, TTL
• Standardized connections: square socket (DIN 3121), 1/4" hex (DIN 3126), or cylindrical shaft ends

What it is used for

Some of the use cases for the 4502A include:

• Bolting and assembly — dynamic detection of starting torque and breakaway torque
• Power tool control — air, electric, and pulse tools (version H is suitable for pulse tool operation)
• Quality assurance — in production and in the laboratory
• Tool calibration and test stands — with or without mounting base
• Functional checks — tilt procedures and rotation monitoring with version RAU

Main features / advantages

What does the 4502A measure?

Type 4502A torque sensors are strain gage based, non-contact shaft torque transducers, optionally available with integrated rotational angle measurement.

The Mini-Smart torque sensor uses strain gage technology. The torque signal is transmitted from the rotating shaft via frequency modulation and processed as an analog signal of ±0 … 5 V. The rotational angle signal, with two tracks of 360 pulses per revolution each, is available as a TTL signal. An external electrical control input is standard.

Why engineers pick it

• Extremely compact. The smart electronics are integral, so the sensor installs directly between tool and joint without a separate amplifier.
• Interference-resistant output. The active ±5 VDC torque output is electrically isolated from supply and measuring signal.
• Responsive to dynamic peaks. A 3 kHz cut-off frequency captures fast torque peaks in bolting and pulse tool operation.
• Fast to adapt. Standardized 1/4" hex (DIN 3126), square socket (DIN 3121), and cylindrical shaft ends fit tools and test stands without custom adapters.

Which 4502A version do I need?

Nominal speed:

• Up to 18 N·m: 12,000 rpm
• 20 to 160 N·m: 9,000 rpm
• 250 to 1,000 N·m: 7,000 rpm
• Versions with rotational angle measurement: 7,000 rpm

The rated torque and version resolve the part number. Not every range is offered in every version; the full matrix is on the Specifications tab.

When is the 4502A the wrong choice?

• High-speed shafts. Nominal speed tops out at 12,000 rpm (7,000 rpm with angle measurement).
• Torques above 1,000 N·m. The 4502A family ends at 8,851 lbf·in (1,000 N·m).
• Wet or dusty environments. The anodized aluminum housing is rated IP40.
• Side loads. Axial and radial force limits are low on the smallest ranges, for example 20 N axial and 5 N radial on the 0.5 N·m H version.

Configure and order the 4502A

Configure the 4502A by rated torque and version, add the cable and mounting accessories you need, and order directly on this page. For questions, contact us.