A servo-grade planetary gearbox range for motion control applications, covering inline (PAB, PPG) and right-angle (PABR) configurations with rated output torque from 9 N·m to 2000 N·m across frame sizes from 40 mm to 220 mm. Three backlash grades are available so the gearbox can be matched to the accuracy the application actually needs rather than to a single catalogue tolerance. Helical gearing throughout, taper roller bearings for axial and radial load capacity, and full compatibility with standard servo and stepper motor adapters.
A precision planetary gearbox is a servo reducer built to a specified backlash tolerance, so that when the motor reverses, the output shaft follows without a measurable dead band. That is the difference between a general-purpose planetary reducer and a precision one: general reducers are rated on torque and life, while precision units are rated on backlash, torsional rigidity and repeatability, because those are what determine whether a positioning axis can hit its target.
This range covers three series across two shaft configurations. The PAB series is the inline (coaxial) high-precision range in seven frame sizes from 042 to 220, with one-stage ratios from 3:1 to 10:1 and two-stage ratios from 15:1 to 100:1. The PABR series is the right-angle version of the same gearbox, using a helical bevel input stage to turn the drive through 90 degrees in the same frame sizes, which is what allows a servo motor to be mounted along the machine axis rather than projecting out from it. The PPG series is a lower-torque inline range in sizes 040 to 160, suited to lighter axes where the torque requirement is below approximately 420 N·m.
All three use helical gearing rather than spur gearing, which raises the contact ratio so load is shared across more than one tooth pair at a time. The practical result is lower noise and higher torsional rigidity at the same torque — both of which matter on a machine tool or a robot axis where the gearbox sits close to the work. Output is carried on high-precision taper roller bearings, which take the axial and radial loads imposed by a timing pulley, a pinion or an overhung load without transferring them to the motor bearings.
Content correction required: the source page text names a different manufacturer as the designer of this gearbox and claims patents and a five-year warranty that belong to that company. That passage has been removed. Please confirm what warranty and what certifications Raydafon actually provides for this range before publication. The wider range is indexed under planetary gearbox and gearbox, with a washdown variant covered by the worm gearbox range where corrosion rather than precision is the constraint.
The table below sets out the three series side by side. Frame size, ratio, backlash grade, output shaft diameter and efficiency differ between them, so the first step in selection is deciding which series fits the torque and the mounting envelope before looking at individual ratios.
Series comparison. Scroll the table sideways on a mobile device to read every column.
| Series | Stage | Frame sizes | Ratio | Rated torque | Output flange dia. | Output shaft dia. | Backlash | Efficiency |
|---|---|---|---|---|---|---|---|---|
| PAB (inline) | 1 | PAB042, 060, 090, 115, 142, 180, 220 | 3, 4, 5, 6, 7, 8, 9, 10 | 14–2000 N·m | 42–220 mm | Φ13, Φ16, Φ22, Φ32, Φ40, Φ55, Φ75 | ≤1, ≤3, ≤5 arcmin | ≥97 % |
| PAB (inline) | 2 | PAB042, 060, 060A, 090, 090A, 115, 142, 180, 220 | 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100 | 14–2000 N·m | 42–220 mm | Φ13, Φ16, Φ22, Φ32, Φ40, Φ55, Φ75 | ≤3, ≤5, ≤7 arcmin | ≥94 % |
| PABR (right angle) | 1 | PABR042, 060, 090, 115, 142, 180, 220 | 3, 4, 5, 6, 7, 8, 9, 10, 14, 20 | 9–2000 N·m | 42–220 mm | Φ13, Φ16, Φ22, Φ32, Φ40, Φ55, Φ75 | ≤2, ≤4, ≤6 arcmin | ≥95 % |
| PABR (right angle) | 2 | PABR042, 060, 090, 115, 142, 180, 220 | 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, 200 | 14–2000 N·m | 42–220 mm | Φ13, Φ16, Φ22, Φ32, Φ40, Φ55, Φ75 | ≤4, ≤7, ≤9 arcmin | ≥92 % |
| PPG (inline) | 1 | PPG040, 060, 080, 080A, 120, 120A, 160 | 3, 4, 5, 7, 10 | 9–423 N·m | — | Φ10, Φ14, Φ20, Φ25, Φ40 | ≤6, ≤8 arcmin | ≥97 % |
| PPG (inline) | 2 | PPG040, 060, 080, 080A, 120, 120A, 160 | 15, 16, 20, 25, 30, 35, 40, 50, 70, 100 | 9–423 N·m | — | Φ10, Φ14, Φ20, Φ25, Φ40 | ≤8, ≤10 arcmin | ≥94 % |
Data conflicts to resolve before publication: three figures differ between the source body text and the source parameter table. (1) Backlash: the body text states ≤2/≤4/≤6 arcmin for one stage and ≤4/≤7/≤9 for two stages, while the table states ≤1/≤3/≤5 and ≤3/≤5/≤7 for the PAB series. (2) Efficiency: the body text gives ≥95 % one-stage and ≥92 % two-stage as blanket figures, while the table gives ≥97 % and ≥94 % for PAB and PPG and ≥95 % and ≥92 % for PABR. (3) Torque: the body text states 9–2000 N·m, while the table gives 14–2000 N·m for PAB and PABR and 9–423 N·m for PPG. Backlash and torque are the two figures a servo application is selected on, so the table above follows the parameter table throughout and the body text values should be deleted rather than reconciled by guesswork.
Every component in a precision reducer has to hold its geometry under load, because backlash is measured at the output and any deflection anywhere in the train appears as lost motion. The materials and treatments below are what keep that loss within the stated tolerance.
Aluminium alloy die casting, ADC12. ADC12 is a die-cast aluminium-silicon alloy chosen for dimensional stability and stiffness at low weight. The housing carries the output bearing bores, so its rigidity directly affects how much the output shaft deflects under an overhung load.
40Cr chromium alloy steel. The ring gear is the internal-tooth member that all planet gears react against. 40Cr is through-hardened and tempered for a combination of core toughness and surface wear resistance, and the internal teeth are finish-machined after heat treatment to hold the tooth spacing that backlash depends on.
20CrMnTi, case-hardened to HRC 58–62 at the surface with an HRC 33–40 core. This is the classic carburising steel combination: a very hard, wear-resistant surface layer over a tough core. The hard case resists pitting at the tooth flank, while the softer core absorbs shock loading without cracking.
High-precision taper roller bearings. Taper rollers take combined radial and axial load, which is what an output shaft carrying a timing pulley, a pinion or a chain sprocket actually imposes. They also set the output shaft's axial location, so their preload affects backlash.
Keyed hollow shaft with motor adaptor. The motor shaft enters a clamping or keyed hollow input, and the adaptor flange is machined to the motor's mounting pattern. This is what makes the gearbox compatible with standard servo and stepper motors rather than tied to one brand.
Keyed solid shaft or keyless solid shaft. The keyed version suits a pulley or sprocket retained on a key; the keyless version uses a clamping arrangement where a keyway would weaken the shaft or introduce unbalance at speed. Both are available across the PAB and PABR frame sizes.
Applicable motors: servo motors and stepper motors. Because the input flange is machined to the motor mounting pattern and the hollow input matches the motor shaft diameter, the gearbox is specified together with the motor rather than independently. Send the motor brand, frame size, shaft diameter and flange drawing when enquiring, and confirm the clamping arrangement matches the shaft — a smooth shaft and a keyed shaft need different input hardware.
Selection runs in a fixed order, because each step constrains the next. Doing it in the wrong order is how a gearbox ends up either oversized and expensive or undersized and short-lived.
The low backlash planetary gearbox page covers the tighter grades in more detail, and the single stage planetary gearbox page explains when a one-stage unit is preferable to a two-stage one.
A precision gearbox is delivered with its backlash set at the factory. Almost everything that destroys that setting happens at installation or in the first few hours of running, so the commissioning steps matter more than the maintenance interval.
Precision planetary gearboxes are specified wherever an axis has to move to a position and hold it, rather than simply transmit power. The common duties are as follows.
The same range serves two very different requirements. A servo axis needs the tightest backlash grade the machine can justify, while an agricultural drive such as a feed mixer or a rotary tiller needs torque capacity and durability and is indifferent to a few arcminutes of lost motion. Specify which requirement dominates when enquiring, because the two lead to different series and different frame sizes within this range.
Send the required output speed and torque, the positioning accuracy you need so the backlash grade can be fixed, the motor brand, frame size and shaft diameter, and whether the mounting allows an inline or requires a right-angle unit. We will confirm the series, frame size, ratio and backlash grade, and reply with a quotation.
Request a Quotation* Parameter values are taken from the series parameter table. Where the source body text quoted different backlash, efficiency or torque figures from the parameter table, the table values have been used and the discrepancy is flagged above for confirmation. Confirm frame size, ratio availability and backlash grade against the current catalogue before designing around them.
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