81-50 4140/2-06965

External toothed 31 51 Standard design
  • External toothed 31 51 Standard design
  • External toothed 31 51 Standard design
  • External toothed 31 51 Standard design
  • External toothed 31 51 Standard design
  • External toothed 31 51 Standard design

81-50 4140/2-06965-External toothed 31 51 Standard design

31 and 51 series slewing bearings are robust double-row ball units with external gear construction, designed to handle moderate to heavy combined loads in general rotary machinery. Featuring two parallel rows of steel balls and integrated outer gear teeth, these bearings deliver upgraded load capacity and built-in transmission functionality in a compact sectional size. Optimized for intermittent duty cycles, frequent start-stop operation and continuous rotary motion, this series serves as a dependable all-round solution for construction, logistics and industrial rotary equipment.


Typical Applications:

Medium to large cranes and excavators

Tower cranes and mobile cranes

Wind turbine yaw and pitch systems

Large solar tracking arrays

Radar and antenna positioning systems

Heavy-duty industrial turntables


High load-carrying capacity
Resistance to high and low temperatures
Noise-free operation
Strictly controlled tolerances and appropriate internal clearance
Long service life and low maintenance requirements
Prevention of unexpected downtime (avoiding bearing fracture, seizure, and safety incidents caused by such failures, with anti-tilting capability)

Dimension and Parameters

External toothed 31 51 Standard design
Type :81-50 4140/2-06965
Brand :LYMC
Drawing No. :Drawing 4
Outside Diameter, Outer Ring
Da [mm] :4456
Inside Diameter,Inner ring
di [mm] :3970
Inside Dia Outer Ring
Di [mm] :4175
Outside Diameter Inner Ring
da [mm] :4178
Weight
G [kg] :3282
Pitch Arde Diameter Outer Ring
La [mm] :4285
Pitch Arde Diameter Inner Ring
Li [mm] :4030
Number Of Holes Per Pitch Circle
n :90
Pitch Circle Diameter
do [mm] :4400
Module
m [mm] :20
Number of Teeth
z2 :220
Addendum Midiffication Coeff
x2 :0.5
Permissible Tooth Force
fznorm [kN] :260
Maximum Permissible Tooth Force
f2max [kN] :465
Static
Co rad [kN] :4750
Co axT [kN] :23588
Co axH [kN] :19508
Dynamic
Crad [kN] :844
CaxT [kN] :2002
CaxH [kN] :1587

Characteristics

✦ Double-row ball arrangement – Two axially spaced rows of balls provide a wide load-bearing footprint.

✦ External gear on outer ring – Gear teeth machined directly onto the outer ring circumference for pinion drive integration.

✦ Separate raceway hardening – Each of the two raceways is induction-hardened individually to ensure consistent surface hardness.

✦ Through-hardened gear teeth – Gear teeth undergo through-hardening or induction hardening depending on module size.

✦ Multi-seal configuration – Each ball row is sealed independently with its own NBR lip seal on both sides.

✦ Heavy-gauge ring sections – Increased cross-sectional thickness compared to single-row designs for added structural rigidity.


Features

✦ Optimized load distribution – Dual-row ball arrangement ensures even load sharing across both rows, reducing peak stress on any single contact point.

✦ Superior moment rigidity – The wide spread between the two ball rows provides exceptional resistance to tilting moments, ideal for high-offset loads.

✦ Enhanced gear durability – External gear teeth are induction-hardened and precision-ground to maintain accurate engagement under intermittent shock loads.

✦ Reduced downtime – Modular seal design allows quick inspection and replacement without full disassembly of the bearing.

✦ Adaptable mounting interface – Bolt-hole patterns are available in both standard and custom configurations to match diverse host structures.

✦ Smooth slew control – Optimized raceway curvature minimizes friction variation, enabling precise positioning even at low speeds.


Further Reading