The so-called bearing clearance, referring to the bearing shaft or the bearing is not installed in the box when one of the inner or outer ring fixed, and then they are not fixed and either the radial or axial movement amount of movement. According to the direction of movement can be divided into radial clearance and axial clearance.
    When operating with a clearance (clearance work called) the size of the rolling bearing fatigue life, temperature, noise, vibration and other performance impact.
    When measuring the bearing clearance, in order to obtain a stable measurement value, the general measurement requirements imposed on the bearing load.
    Thus, the resulting measured value is greater than the true clearance (clearance called theory), which means the increase of the load generated by measuring the amount of elastic deformation.
    However, to the roller bearings, since the elastic deformation is small, negligible.
    Install the front bearing internal clearance clearance representation theory for general use.
    Package bearing radial clearance measurement is not easy to measure force itself and its rings and rolling contact at the elastic deformation, the deformation is caused by multiple factors, measurement error, it measuring force, contact state and rolling elements position are related. Bearing swivel flexibility generally in a horizontal position check, usually the inner ring fixed (or handheld inner), hand rotating outer ring, check whether there is abnormal bearing rotation noise and blocking phenomenon. In general, the duration of bearing rotation length, stop slow, flexibility like. Conversely, a short rotation time, stop suddenly, flexibility is good. Due to bearing structure type and different sizes, the flexibility of its rotation should have different requirements. Such as single row radial ball bearings, single row angular contact ball bearings, rings due to rolling contact between the body and the area is small, these bearings are rotated relatively light, while the double row radial spherical roller bearings and thrust bearings, due to rolling element and raceway contact area is large, while the outer ring has a smaller weight in check when its rotation flexibility, though with a certain load, but are not as brisk single row radial ball bearings. For large bearings, when it rotates, there should be no stuck phenomenon, but generally not the rotary sound check. For tapered bore bearings, bearing the following ways supplementary examination rotation flexibility, as follows: the tapered bore bearings pressed into the mandrel until the plus certain radial preload, in this pre-load, when a ferrule listen to a rolling rotation should rotate. If the slide instead of rolling rotation, then the ferrule geometry defects excessive or uneven size rolling element bearing rotation flexibility is also poor.
    Measuring bearing radial clearance Precautions
    (A) as far as possible using a dedicated instrument measurement.
    (2) Measurement of hand-push method requires measurement had higher measurement skills. This method is the measurement error is large, especially clearance marginalized state, prone to error, this time, the instrument should measure shall prevail.
    (3) feeler gauge, the provisions of the standard operation should not be used on the feeler roller from rolling past measured.
    (4) the measurement process, should ensure that the ball fall into the ditch; closed before the closure of the bearing measurement; using a Dutch instrument, the measured value minus the load should be increased due to the amount of clearance.
    (5) For multi-row bearings, clearance eligibility requirements for each column, each row clearance to take the arithmetic mean of the bearing radial clearance.