A flat, grease- and oil-free rest is essential for the upper and lower ring to seat solidly. Rothe Erde recommend examination of the bearing surfaces with a levelling instrument or laser machine. Only in exceptional cases for bearings Ø 2,5 m (with corresponding large cross sections) a feeler gauge should be used.

With the feeler gauge measuring method, it is recommended that after the first measurement the bearing is offset by 90° and the measurement repeated.

Machining of the contact area, as a final manufacturing step is necessary (after welding). Welding beads, burrs and strong paint residues and other uneven surfaces are to be removed.

Dependent upon the design type and the track diameter “DL” of the bearing, the maximum out-of-flatness including the slope “P” (mm) of the upper or lower contact surface should not exceed the values shown in Table 8.

Regarding the slope of the machined surfaces, the figures shown in the table refer to a support width of 100 mm.

To avoid larger deviations and the occurrence of peaks in smaller sectors, any deviation in the range of 0° – 90° – 180° may only rise or fall gradually. Prior to installation, the bearing should be checked for smooth running by rotating the unbolted bearing around its axis, twice.

Should the permissible out-of-flatness, including the slope, be exceeded, we recommend that the contact surfaces for the bearing be machined.

For bearings of standard series KD 320, RD 700 and RD 900 the bearing has to be installed as shown on the drawing.

Remove the protective coating from the bearing’s upper and lower support surfaces as well as from the gear. No solvent should be allowed to come in contact with the seals and raceways. Do not clean the gears if these are greased.

Diameter tolerances

Machined diameters with untoleranced drawing dimensions have the following tolerances:

≤ 315 mm	± 1.6 mm
≤ 1,000 mm	± 2.5 mm
≤ 2,000 mm	± 3.5 mm
≤ 4,000 mm	± 5.0 mm
≤ 6,300 mm	± 7.0 mm
≤10,000 mm	± 10.0 mm

All grease nipples must be easily accessible. If necessary, grease pipes should be provided to allow relubrication through all grease connections. We recommend automatic lubricating systems.

Hardness gap
The unhardened zone between the beginning and end of the hardened region of the raceway is identified by a punched-in letter “S” near the type plate or filler plug at the inner or outer diameter of each bearing ring. On the gear ring, the hardness gap is marked on the axial surface. On the ring with a point load the hardness gap “S” must be positioned outside the main load-carrying areas.

Gearing
It has to be warranted, that the backlash is adjusted at 3 teeth marked in green and is to be at least 0.03 x module. After the final tightening of the bearing the backlash should be rechecked over the entire circumference.

A tip edge radius and a tip relief must be provided on the pinion.

Check that the bolt holes in the bearing line up with the holes in the companion structure. Otherwise, the bearing may become stressed. Through holes must conform with DIN/ISO 273, medium series see Table.

Standard strength class for fastening bolts (without surface treatment): 10.9 to DIN 267.

The quantity and diameter specified must be absolutely adhered to. Bolts must be carefully preloaded crosswise to specified values (Table gives several recommended values).

The surface pressure under the bolt head or nut must not exceed the permissible maximum value.

When the permissible pressure is exceeded, washers with the respective size and strength have to be provided. The minimum bolt length must be assured. If a hydraulic tensioning device is applied, corresponding washers have to be used (see Prestressing of fastening bolts).

The determination of the tightening torque depends not only on the strength class of the bolt and the tightening process, but depends on the friction in the thread and on the area surface bolt head and nut. The tightening torques given in the table are recommended values based on lightly oiled threads and contact surfaces. Dry threads will require higher torques whilst heavily oiled threads will require lower tightening torques. The values may, therefore, vary considerably. This applies in particular to M 30 or 11/4“ threads and larger. For bolts of this size and larger we recommend the use of hydraulic tensioning devices.

Welding of the bearing or welding in the vicinity of the bearing is not permitted as the heat generated may cause distortions. Exceptions to this rule will require previous approval from us.

Thread/bolt diameter	Drilling diameter	Tightening torque Nm with bolts with a strength class μG ≈ μK = 0.14
	mm	for hydr. Md torque wrench	for Md key	for hydr. Md torque wrench	for Md key
	DIN/ISO 273	8.8	8.8	10.9	10.9
M 12	14	87	78	130	117
M 14	16	140	126	205	184
M 16	17.5	215	193	310	279
M 18	20	300	270	430	387
M 20	22	430	387	620	558
M 24	26	740	666	1,060	954
M 27	30	1,100	990	1,550	1,395
M 30	33	1,500	1,350	2,100	1,890
		Grade 5	Grade 5	Grade 8	Grade 8
UNC 5/8'' -11	18	200	180	286	260
UNC 3/4'' -10	21	352	320	506	460
UNC 7/8'' -9	25	572	520	803	730
UNC 1'' -8	27.5	855	770	1,210	1,100
UNC 11/8'' -7	32	1,068	970	1,716	1,560
UNC 11/4'' -7	35	1,507	1,370	2,410	2,190
		Grade 5	Grade 5	Grade 8	Grade 8
UNF 5/8'' -18	18	230	210	320	290
UNF 3/4'' -16	21	396	360	560	510
UNF 7/8'' -14	25	638	580	902	820
UNF 1'' -12	27.5	946	860	1,330	1,210
UNF 11/8'' -12	32	1,210	1,100	1,936	1,760
UNF 11/4'' -12	35	1,672	1,520	2,685	2,440