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Brand: SKF
SKF TKRS 21 High Power LED Stroboscope, 30-300 000 FPM
Description
Freezing motion to see how a machine really runs
The SKF TKRS 21 is a compact stroboscope for visual inspection of running machines. Seven ultra-bright LEDs make it a very bright stroboscope in pocket format, with a multi-line backlit TFT screen and an ergonomic design. It is supplied in a sturdy carrying case with three AA batteries included. When the flash frequency matches the speed of a rotating or reciprocating part, the part appears to stand still, so a belt, fan blade, coupling, gear or chain can be checked while the machine runs.
SKF lists inspection of rotating machines with bearings, gears, belts, fans and chains, and the instrument is also used in the textile industry for pattern inspection. The TKRS 21 offers flash mode and tachometer mode, a phase shift function and a tripod connector (1/4-20 UNC). Unlike its sibling TKRS 31, it has no laser speed measurement and no external trigger.
Technical specifications
| Parameter | Specification |
|---|---|
| Flash rate range | 30 to 300 000 flashes per minute |
| Flash rate accuracy | +/-0.005 % (+/- 1 digit at 23 C) |
| Flash setting resolution | +/-0.1 (30 to 999.9 f/min); +/-1.0 (1 000 to 300 000 f/min) |
| Flash source | 7 LEDs |
| Flash duration (brightness) | Adjustable, 0.2 degrees / 1 microsecond to 5 degrees / 2 000 microseconds |
| Light power | Above 5 600 lux at 3 degrees flash duration and 0.3 m |
| Flash colour | Approx. 5 000 to 8 000 K |
| Display | Multi-line backlit TFT |
| Power source | 3 x AA batteries (included, rechargeable types also usable) |
| Run time per charge | About 3 h at 1 degree and full display brightness; about 6 h 45 min at 0.2 degrees and 20 % brightness |
| Auto switch off | 10 min, 5 min or off |
| Instrument dimensions | 225 x 78 x 50 mm (8.9 x 3 x 2 in.) |
| Case dimensions | 260 x 85 x 180 mm (10.2 x 3.3 x 7.1 in.) |
| Instrument weight / total weight | 0.29 kg / 0.78 kg |
| Operating temperature | 0 to 40 C (32 to 104 F) |
| Protection | IP30 (indication only) |
Using a stroboscope safely
The manual warns that stroboscopic light can trigger epileptic seizures in persons at risk and that flashing light can damage the retina, so never stare into the LEDs. Keep clear of rotating parts, because a stopped-looking image is only an optical effect. Match the flash rate to the machine speed, then use phase mode to move the apparent position. Read the safety section of the manual before use.
What to confirm before ordering
If you need to measure speed with a laser or trigger the flash from a machine signal, the TKRS 31 is the version with those features. Confirm the speed range of your machine against 30 to 300 000 f/min. Hand-held diagnostic instruments are listed under Portable Test & Measurement, for example the SKF TKRT 31 tachometer.
In practice, a stroboscope is quick for checking belt condition, fan blade behaviour, coupling movement and chain movement without stopping the machine. Reflective tape on a shaft helps you see the stopped image. Take readings with the flash rate set slightly above or below machine speed to see slow apparent rotation, and record the speed shown on the display for the maintenance report.
Documents and quotation
The SKF instructions for use covering the TKRS 21 and TKRS 31 are attached; the SKF product page quotes 6 200 lx, and this page follows the manual. Send quantity and delivery point for a quotation.
Datasheets & Documents
- Manual SKF TKRS 21 and TKRS 31 instructions for use (MP5487, June 2026, multilingual) Download
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About brand
SKF is the Swedish bearing manufacturer founded in Gothenburg in 1907. The company was built on the self-aligning ball bearing developed by engineer Sven Wingquist, who became its first managing director. Today SKF also makes seals, lubrication systems, condition monitoring equipment and maintenance tools.
Seven Star LLC is an independent supplier in Muscat. We list SKF bearings, greases, automatic lubricators, condition monitoring sensors and maintenance tools, and supply them to maintenance teams in Oman and the GCC by designation.
SKF company profile
| Established | 1907, Gothenburg, Sweden; first factory built in 1908 |
|---|---|
| Founding product | Sven Wingquist's self-aligning ball bearing |
| Name | From Svenska Kullagerfabriken, Swedish for "Swedish Ball Bearing Factory" |
| Product families | Rolling bearings, seals, lubricants and lubrication systems, condition monitoring sensors and analysers, and maintenance tools for mounting, alignment and dismounting |
Milestones
- 1907: Sven Wingquist's self-aligning ball bearing is patented and SKF is founded in Gothenburg.
- 1908: The first factory is built.
- 1912: SKF is represented in 32 countries.
- 1926: SKF sets up AB Volvo as a subsidiary to build cars; the first production car follows in 1927.
- 1935: Volvo becomes an independent company.
SKF products we list
| Family | Models | Typical use |
|---|---|---|
| Bearings | 6205-2RSH/C3, 6206-2RS1, 6314, 7312 BECBM | Motors, pumps, fans and gearboxes |
| Greases | LGMT 2, LGMT 3, LGEP 2, LGWA 2, LGHP 2, LGHB 2, LGEV 2 | General, heavy-load, high-temperature and slow-speed bearing lubrication |
| Automatic lubrication | TLSD, LAGD 125 (ATEX), TLMR, TLMP 1008, TLGH 1 grease gun | Steady greasing of hard-to-reach or many lubrication points |
| Condition monitoring | Microlog Analyzer AX, CMSS 2200, CMSS 793-EE (ATEX), TKRS 21 stroboscope, TKRT 31 tachometer | Vibration routes, permanent sensors and speed checks |
| Alignment | TKSA 41 shaft alignment, TKBA 40 belt alignment, TMAS shims | Laser alignment of couplings and belt drives |
| Mounting and dismounting | TIH 030m, TIH 100m, TIH 220m heaters, TMFT 36, TMMA 75H, TMMP 10, TMHP 30/170 pullers, TMJL 100 pump | Fitting and removing bearings without damage |
An SKF designation describes the bearing exactly. In 6205-2RSH/C3, "62" is a light-series deep groove ball bearing, "05" means a 25 mm bore (05 × 5), "2RSH" means rubber seals on both sides, and "C3" means internal clearance larger than normal, which motors often need because the inner ring runs warmer than the outer. Choosing the right grease matters just as much: a general grease such as LGMT 2 suits most motors, while heavy loads, high temperatures or slow speeds need an EP, high-temperature or high-viscosity grade.
Where SKF products are used
In Oman and the GCC, SKF bearings, lubricants and tools are used by maintenance teams in oil and gas, power and desalination, cement, mining, steel, water and food plants, and by motor and pump repair workshops.
Ordering SKF products: what we need
Send the full bearing designation including all suffixes (seals, clearance, cage), and the quantity. For greases, send the grade and pack size. For tools and lubricators, send the model and, for heaters, the largest bearing weight and bore you need to heat.
Facts checked against SKF company history, October 2026.
Browse SKF products by category: Electromotors.
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Frequently Asked Questions
What flash rate range does the TKRS 21 cover?
30 to 300 000 flashes per minute with +/-0.005 % accuracy.
How bright is it?
Above 5 600 lux at 3 degrees flash duration and 0.3 m, according to the manual.
What power does it use?
Three AA batteries, supplied with the instrument, with about 3 hours of run time at full brightness.
What is the difference from the TKRS 31?
The TKRS 31 adds laser tachometer functions and an external trigger input; the TKRS 21 has neither.
What is supplied in the case?
The stroboscope, operating instructions and three AA batteries in a carrying case.
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