Type SC – Servo worm gearboxes


  • Gear ratios: i = 10:1 up to 20:1 (i>20 upon request)
  • Maximum acceleration torques on output: 1100 Nm
  • 5 gearbox sizes ; centre-to-centre distance: 040 to 100 mm
  • Minimised circumferential backlash (optional)
  • Housing made of grey cast iron
  • Worm gearboxes suitable for fitting servo-motors
  • Non-positive connection between motor and gearbox

The example shows the construction type B0

The order code reflects the customer specifications.

Type Size Gear ratio Model Fixing side Installation position Speed n2 Design
SC 050 5:1 B0- 1. 1- 600 /0000
Description Size; Table 11.5.15‑1 Table 11.5.15‑1 Figure 11.5.15‑1 Side on which fixing is made; Table 11.5.4‑1 Side directed downwards; Figure 4.3.1-1

Gearbox sides

Slowly rotating shaft

Table 11.5.15‑1

Will be determined by ATEK
V080- / 14 x 30 No. 301 KN
Flange Motor shaft Ø x length Flange no. See chapter “Coupling”

General construction

The SC AdServo gearboxes are based on the proven worm gearboxes of the S-type series. In worm gearboxes, both shafts intersect in a defined distance (A).
This centre-to-centre distance is reflected in the specification of the gearbox size.
(Example: S 100 – centre-to-centre distance 100  mm)


A gear set consists of worm shaft and worm gear.

The worm shaft made of carburised steel is hardened, the toothing is ground.
The worm gear consists of a high-quality bronze alloy, the toothing is milled.

Construction types

Due to the modular system, different gearbox construction types can be configured.
The variants differ in the type of the shafts, the rotational direction of the shafts, and the support by bearings.

Threaded mounting holes

All sides of the gearboxes are machined.
The housing surface on the side 1 and the flange surfaces on the sides 5 and 6 may be used as mounting surfaces.
All flanges always have threaded mounting holes.

You have the following available ordering options:



Please enquire other mounting options.
The standard version of the mounting / fastening has the order code 9.
Example of order code: HC 090 12:1 D0 9.1

Installation position

The installation position is defined by the gearbox side directed downwards during operation and will be indicated by the corresponding numeral.
The following is an order code example with the numeral 2. Order code example: SC 050 5:1 B0 -1.2-600/0000
Principally, the gearboxes can be used in all installation positions.
The technically most favourable and thus recommended installation position is the installation position 1, in which the worm shaft is horizontal and located at the bottom.

For an optimal technical design of the gearboxes, we always ask to specify the installation position.
The performance data and torques listed in the selection tables are only valid if the gearboxes are used in the installation positions 1, 5 or 6.
The values must be reduced by 10% if the worm shaft is vertical or located at the top (installation position 3, 4 or 2).

Shaft designation – allocation to the gearbox sides

The worm shaft is the fast-rotating shaft.

It has the speed n1 and is identified by N1.

The slowly rotating shaft has the speed n2 and is identified by N2.
The worm gear is located on this shaft.

The gearbox sides are identified by the numerals 1 to 6.

For the allocation to the gearbox sides, please refer to the following figure and the Figure 4.2.1‑1 Gearbox sides.



Rotational direction and gear ratio

As standard, the worm gearboxes are delivered with right-handed worm gear sets.
This results in the rotational directions according to Figure 11.5.6-1.
In the special design, delivery with left-handed gear teeth is also possible.
Please enquire this.
For the possible gear ratios, please refer to the performance tables.
Principally, the actual gear ratio “iist” must be taken into account for the layout.
In some cases, this deviates from the nominal gear ratio i.


The achievable efficiency depends on rotational speed, torque, installation position, sealing, and lubricant type.

Starting Efficiency

The efficiency is always lower during the starting phase and in the cold operating state of the worm gearbox since the lubricating film is not formed until the sliding motion has started.
Therefore a higher torque is needed.
The starting efficiencies listed below are guidance values and valid for run-in gearboxes.
These starting efficiencies must be taken into account for the layout.




Operating Efficiency

The tooth flanks of worm gearboxes in the as-delivered condition are not yet fully smoothed.
This influence is even increased with high gear ratios.
Therefore the gearboxes should be run in with approx. 50% of the nominal data, if possible, before they are operated under load.
The efficiencies specified in the performance tables relate to the permissible nominal data and are guidance values for run-in gearboxes with standard sealing that have operating temperature.



Different conditions for the lubrication of the toothing and the roller bearings will arise depending on gearbox size, installation position, rotational speed and on-period.
In order to ensure these optimally, different oil quantities and viscosities are used.
These will be defined by ATEK based on your ordering details (rotational speed, on-period, and ambient temperature).
They will be reflected in the abbreviation code of the type designation.

Example: SC 125 10:1 C0 -9.1- 200/A1
/A1 means:




The ATEK worm gearboxes are factory-filled with synthetic polyglycol oil and are normally maintenance-free.
Oil viscosity and venting option are dependent on the rotational speed
Operating mode: cyclic operation S1


For the meaning of the abbreviations A through E and 0, 1, please refer to the following tables.
Oil viscosity table



Injection lubrication may be necessary in case of high rotational speeds and large gearboxes.
In case of very low rotational speeds, lubrication by fluid grease is also possible.
At operating temperatures over 50°C, high pressure will develop through air expansion in the gearbox.
Then a permanent pressure compensation must be ensured.
To this end, the use of a vent filter is prescribed.




Vent filter

If venting is required the gearboxes will be delivered with a vent filter.
The vent bores will be equipped with screw plugs for transport.
The vent filter will be enclosed as a separate item and must be mounted in the intended position prior to commissioning.
An elbow may be required.
The position will be specified in the order documents.
Please refer to the table below for the position of the filter.
Here, E4, for example, means: Venting on side 4.


Low-backlash construction

For optimal running, the tooth space in the gear set is manufactured larger than the tooth.
When the direction of rotation is changed, this results in a rotation angle until the counter-rotating tooth flanks contact each other.
This rotation angle is called circumferential backlash.

Circumferential backlash, measuring method

The circumferential backlash is measured after the drive shaft (N1) has been fixed.
A force of around 2% of the nominal torque is applied to the output shaft (N2) in both rotational directions.
A tooth backlash will result between the two final positions. This can be measured as rotation angle and is indicated in minutes of arc [arcmin].

Circumferential backlash, type

All ATEK worm gearboxes can be delivered as low-backlash types.
The following values can be set with standard gear sets for the different gearbox sizes:



Abbreviation: u.r.
– upon request


Connection of drive shaft to coupling

For torque transmission, a zero-play coupling is located on the drive shaft.


Two congruent coupling halves are positively connected by means of a plastic toothed ring under pretensioning.
In case of extreme peak tensions and impact loads (emergency shut-off), a damping action is achieved through a slight distortion in the elastic range.
The coupling is axially insertable and compensates angle errors as well as misalignments in the radial and axial direction.
A later changeover to another motor is easily possible.
The motor-side coupling hub is available in the following variants:




Depending on the variant KN or KNN/SN, different torques can be transmitted.

Design of the coupling

Due to the dynamic characteristics of the servo-motors, the permissible acceleration torque and the emergency-stop torque must be considered when designing the servo gearboxes.
The correct coupling hub can be selected by means of the table below on the basis of the maximum permissible torques on the motor shaft, acceleration torques (T1B) and emergency-stop torques (T1Not).

Motor mounting

The servo-motor will be bolted to the motor flange of the gearbox on side 3.
The flange number of the motor flange for the respective gearbox size is to be determined in Table 11.5.14-1.

Motor flange

ZK:     Diameter of centring circle
LK:     Diameter of pitch circles
L:      Length of motor shaft
d:      Diameter of motor shaft
i:      Centring height
s:      Thread
The values for the centring height (i) and the thread sizes (s) can be found on the respective pages.


The values for the centring height (i) and the thread sizes (s) can be found on the respective pages.
Fitting dimensions of the servo-motor – gearbox size/flange no. (selection)

Type overview