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NTN - Large Bearings

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Lubrication<br />

Where speeds are high and temperature rises need to<br />

be kept to a minimum, a reduced amount of grease<br />

should be used. Excessive amount of grease cause<br />

temperature rise which in turn causes the grease to<br />

soften and may allow leakage. With excessive grease fills<br />

oxidation and deterioration may cause lubricating<br />

efficiency to be lowered.<br />

Solid grease<br />

6.4 Solid grease (for bearings with solid grease)<br />

"Solid grease is a lubricant composed mainly of<br />

lubricating grease and ultra-high polymer polyethylene.<br />

Solid grease has the same viscosity as grease at normal<br />

temperature, but by applying a special heat treatment<br />

process, this special grease solidifies retaining a large<br />

proportion of the lubricant within the bearing. The result of<br />

this solidification is that the grease does not easily leak<br />

from the bearing, even when the bearing is subjected to<br />

strong vibrations or centrifugal force.<br />

<strong>Bearings</strong> with solid grease are available in two types:<br />

the spot-pack type in which solid grease is injected into<br />

the retainer, and the full-pack type in which all empty<br />

space around the rolling elements is filled with solid<br />

grease.<br />

Spot-pack solid grease is standard for deep groove ball<br />

bearings, small diameter ball bearings, and bearing units.<br />

Full-pack solid grease is standard for self-aligning ball<br />

bearings, self-aligning roller bearings, and needle roller<br />

bearings.<br />

Primary advantages:<br />

(1) Clean working environment with minimal grease<br />

leakage<br />

(2) Low bearing torque with spot-pack type solid grease<br />

Fig. 6.3 Deep groove ball bearing with spot-pack solid grease (Z shield)<br />

(Standard for deep groove ball bearings)<br />

Solid grease<br />

Fig. 6.4 Self-aligning roller bearing with full-pack solid grease<br />

(Standard for self-aligning roller bearings)<br />

For more details, please refer to the <strong>NTN</strong> special catalog<br />

for Solid grease bearings.<br />

A-41

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