High-Precision Compact Planetary Gearbox for Servo Integration — PLS Series (PLS70–PLS190)

The PLS series precision planetary gearbox extends the performance class of our PLE/PLF precision range into a higher torque bracket while maintaining the ≤3 arcmin backlash specification that precision servo applications demand. Five frame sizes from PLS70 through PLS190 deliver rated output torque from 27 N·m up to 1,000 N·m — covering servo motors from compact 50 W units to 5,000 W industrial servo drives in a single series selection framework.

The standout specification is the 14,000 rpm maximum input speed on the PLS70 frame — the highest in our entire 遊星ギアボックス range. This enables direct coupling to high-speed brushless servo motors that run at 6,000–10,000 rpm without requiring intermediate coupling stages or spindle-speed reduction. Sealed lifetime lubrication, IP54 protection, and any-angle mounting make PLS series equally suited to vertical joint actuators in robots, horizontal feed axes in CNC machining centres, and cleanroom-compatible semiconductor handling systems.

High-Speed Laser Cutting

Fiber laser cutting gantry axes drive at 2,000–3,500 W with rapid acceleration demands that stress gearbox backlash at direction reversals. PLS120 and PLS150 maintain ≤3 arcmin through >50 million cutting cycles — preventing the kerf-width variation that develops with standard grade reducers as backlash increases with wear.

Medical Surgical Robot Arms

Robotic surgery systems require absolute repeatability across thousands of identical procedures. PLS70 units in da Vinci-class instrument arms must maintain backlash specification without the mechanical backlash compensation that would introduce algorithm-dependent variability into surgical tool positioning.

Radar & Antenna Systems

Phased-array radar and satellite dish positioning drives require precise azimuth and elevation axis control where backlash introduces pointing error during direction reversal. PLS190 handles the high sustained torque from wind loading on large antenna structures while maintaining ≤3 arcmin pointing repeatability.

For cleanroom applications, PLS series material certificates confirm that no SVHC (Substance of Very High Concern) is used in housing, gear, or lubricant specification — supporting ISO 14644 cleanroom compatibility documentation for semiconductor fab equipment qualification packages.

Factory Acceptance Tests — Every Unit

• ✔ Individual backlash measurement — ≤3 arcmin verified per unit
• ✔ Output shaft runout — radial ≤0.01 mm, axial ≤0.01 mm
• ✔ Full-load efficiency at 50%, 75%, 100% rated torque
• ✔ High-speed noise test at 10,000 rpm input (PLS70/90)
• ✔ IP54 ingress seal test — pressure differential method

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→ Precision CV Drive Shafts

Zero-backlash CV shafts with ≤0.005 mm runout for connecting PLS output flanges to robot forearm links, linear ball-screw ends, and rotary table driven flanges without introducing additional backlash or misalignment-induced bending forces into the gearbox output bearing.

• ▸ Zero additional backlash contribution
• ▸ Runout ≤0.005 mm — cleanroom compatible

→ Self-Locking Worm Gearbox

For vertical robot axes and Z-axis machine tool drives where gravity load requires fail-safe holding torque on power loss, a worm stage downstream of PLS provides self-locking capability without adding backlash to the precision positioning chain — using PLS for accuracy and worm for safety.

• ▸ Self-locking at ratios ≥40:1
• ▸ No external brake required on vertical axes

→ Bevel Stage Power Split

For multi-head precision assembly systems and dual-wrist robot configurations where a single PLS drive must power two perpendicular output axes simultaneously, a high-precision bevel stage splits PLS output power with minimal additional backlash contribution.

• ▸ Precision bevel pairs ≤5 arcmin
• ▸ Efficiency 96–98% per stage

PLS120 units for a 15 kg payload 6-axis robot shoulder joint. The ≤3 arcmin specification was what our simulation required for ±0.05 mm TCP accuracy at 1.4 m reach. After 14 months of 2-shift production, backlash measured at the last maintenance check was still within specification. The per-unit measurement certificate was essential for our ISO 9283 robot acceptance test documentation.

PLS70 on our 300 mm wafer FOUP handler wrist joint. The SVHC-free material certificate was the deciding factor over a Japanese competitor — our fab qualification process requires this documentation. 16 months in Class 1 cleanroom operation with zero particle events or gearbox-related wafer contamination incidents. 14,000 rpm input speed allowed us to use a smaller, lighter servo motor than competitors recommended.

PLS150 for the A-axis on a 5-axis machining centre for titanium aerospace parts. The ≤3 arcmin specification was a hard customer requirement for first-article titanium part acceptance. 18 months later the axis positioning accuracy is still within ±0.025° — better than our spindle calibration interval requires. The IEC adapter plate for our Siemens 1FT7 motor was a perfect fit with zero machining.

PLS120 in a 6 kW fiber laser cutting head gantry — both X and Y axes. After 80 million direction reversals (confirmed by machine counter) kerf width variation is still ±0.03 mm. With our previous standard-grade reducers we were recalibrating every 2 million cycles to compensate for worn backlash. The PLS investment paid back in reduced calibration downtime within 5 months.

QWhat is the difference between PLS and PLE/PLF series?

PLS and PLE/PLF both target precision servo applications with similar backlash specifications. The key differences: PLS achieves ≤3 arcmin vs PLE's ≤4 arcmin; PLS covers larger frame sizes (PLS70–PLS190) with output torque up to 1,000 N·m vs PLE/PLF's approximately 200 N·m maximum; and PLS is designed specifically for high-torque robot joints and CNC rotary tables where PLE/PLF's smaller frames are underpowered. For motors below 1,000 W, PLE/PLF is typically more cost-effective with equivalent precision performance.

QWhy does PLS70 support 14,000 rpm but PLS190 is limited to 6,000 rpm?

Input speed limits are governed by centrifugal loading on planet gear bearings and dynamic balance of the planet carrier. Smaller frames use lighter planet assemblies that sustain higher centrifugal loads at elevated rpm. PLS190's larger, heavier planet gears generate unsafe bearing DN values above 6,000 rpm. This is not a limitation in practice — the 5,000 W servo motors compatible with PLS190 are designed to operate at 3,000–4,000 rpm rated speed, well within the 6,000 rpm limit.

QWill the ≤3 arcmin backlash specification degrade over time?

Under correct application conditions (within rated torque, no shock overloads exceeding 200% rated), PLS backlash drift is below 0.5 arcmin over 30,000 operating hours based on accelerated life test data. The diamond-lapped ring gear surface and matched bearing preloading are specifically designed to prevent the micro-pitting and bearing clearance growth that cause backlash to increase with service time in conventional precision gearboxes. Applications that consistently operate above 90% rated torque will see slightly accelerated wear — design for 70–80% rated torque for maximum service life.

QIs PLS series suitable for cleanroom Class 1 semiconductor environments?

Yes, with the standard sealed configuration. The sealed grease fill has no external vents that could release lubricant vapour into the cleanroom atmosphere. Housing surfaces are smooth and non-particle-shedding. SVHC-free material certificates are provided on request for equipment qualification documentation. For Class M1 (ISO 14644-1) environments, we recommend IP65 sealing option and anodised housing surface finish — specify at time of order.

QWhat servo motor brands are directly compatible with PLS adapter plates?

Standard IEC B5/B14 adapter plates cover: Siemens 1FK7/1FT7, Yaskawa SGMJV/SGMSV, Fanuc αi/βi, Mitsubishi HG-KR/HG-SR, ABB BSM/BSP, and Bosch Rexroth MSK series. For non-IEC motor flange configurations (e.g. Kollmorgen, Parker, Beckhoff), custom adapter plates are machined to order — provide motor flange drawing for feasibility confirmation within 48 hours.

QCan PLS series be used in both horizontal and vertical robot joint orientations?

Yes, all mounting orientations are supported — horizontal shaft, vertical shaft up, vertical shaft down, and intermediate angles. The sealed grease fill does not require orientation-specific lubrication management. For vertical-shaft-down configurations under sustained gravity load, double-lip output shaft sealing prevents grease migration along the output shaft into the robot arm link — this is a standard feature on all PLS units, not a special option.