SNR 6307 FT150 Kugellager (35x80x21)

The principal dimensions are 35x80x21 mm at a weight of 0.46 kg; the further technical details are listed in the specification table. This variant features increased radial clearance (C3). Increased clearance (C3) and a fluoroelastomer point to the same cause: a position at which it is permanently hot. This version differs from an otherwise identical non-contacting variant solely in the material of the sealing body, and that distinction is to be assessed differently at a non-contact seal than at a contact one.

The geometry stays the same: an elastomeric sealing body follows the contour of the inner ring down to a narrow distance without touching it, so no load-independent frictional torque, no additional heat source and no wear point arises, and the permissible speed stays close to that of the open form. Because the sealing body does not bear against the ring, its abrasion resistance is secondary; what counts is its resistance to temperature, ageing and the media of the surroundings, and it is exactly for this that a fluoroelastomer is used.

The material thereby shifts the limit at which the version fails: not wear but embrittlement or swelling of the sealing body would be the governing process with a less resistant material. Increased clearance (C3) fits the same picture, since a permanently elevated temperature at the position consumes part of the mounted clearance together with the interference fit, and the allowance ensures that a residual clearance remains in the warm running state without preloading the rolling contact.

The third constituent affected by the same temperature remains to be checked: the grease charge is enclosed and dimensioned for the service life, and its resistance has to be stated in its own right, because it cannot be inferred from the sealing material. The permissible temperatures for the sealing body and the grease charge are to be taken from the designation.

Independently of this, through-hardened standard bearing steel sets the frame for hardness and dimensional accuracy of the rings; a gap does not hold back liquid permanently.