BEARING INSTALLATION

 Bearing Installation

Cleanliness, proper tools, and specific mounting guidelines are needed to assure proper installation as well as long-lasting bearing performance. Improper bearing installation is a common cause of premature bearing failure.

Pre-installation

Check the shaft and housing

A bearing cannot operate properly if the shaft or housing is not in good condition. Before mounting the bearing, be sure shaft and housing bore dimensions are within recommended tolerances. The bearing seat in the housing bore should be perfectly round and not tapered. The shaft and housing also should be clean and free from nicks and burrs .Extra care should be taken when mounting a bearing in a solid housing. Before any installation pressure is applied, the outer race should be perfectly square with the housing bore.

Check the seal

Check the seal, which will be mounted on the shaft. Also check the shaft. Its condition is just as crucial to correct seal placement as it is to bearing operation. Be sure to follow proper seal installation guidelines and use only the recommended tools. Always replace used seals with new ones. Use the same seal design and size as the original. A seal installed next to the bearing is a sure way to prevent fine dirt, dust, moisture and contaminants from reaching the bearing, while also retaining lubricant.

Bearing assembly

With all parts ready for assembly – bearing, shaft and housing – installation can now begin. Do not remove the bearing from its container until you’re ready to install it. Everything must be clean – tools, hands, work area, shaft and housing

2). Then take the bearing out of its protective wrapper, place it on clean paper and cover it with a lint free cloth or oiled paper. The protective grease or oil coating on the bearing should not be removed. This protective coating was put on by the manufacturer to prevent corrosion, dirt or dust from damaging the bearing before and during use and is compatible with all lubricants. Coat the bearing, housing and shaft with the same lubricant being used in the machinery in which it will be placed. This will ease mounting and prevent rust from building up at the press-fit contact area.

Press-fitting the bearing

Press-fit refers to the amount of interference between the race and the seat: the inner race with the shaft, and the outer race with the housing. If the inner race is press-fit then it will rotate with the shaft. If the outer race is to be press-fit then it will rotate with the housing. One example is in a truck’s front wheel hub. Here, the inner race is mounted with a slip fit on the shaft, while the outer race is press-fit  A press-fit is accomplished by stretching the inner race over a shaft slightly larger than the bore of the bearing. Press-fits that are too tight can also be damaging to the bearing. Too tight a fit squeezes the two races together, preventing the balls or rollers from turning correctly and causing excess heat and wear. The result is premature bearing failure. In applications where only one race is press-fit, the other race gets a slip-fit – or a slightly looser fit. This slip-fit is just as important as the press-fit. When the race is too loose, it will creep up on the shaft or in the housing causing it to slam into the surface on which it is stationed. This results in friction, overheating, excessive wear and contact erosion between the shaft and inner race, or housing and outer race.

Mounting the bearing

Start the bearing on the shaft with the rounded corner of the bearing going on first. Fit a clean pipe over the shaft so that it rests only on the race being press-fit. Be sure the bearing is square on the shaft. Then apply pressure to the press-fit race only. Push the press-fit race firmly against the shoulder on the shaft. If the cup is to be press-fit, for example, apply pressure only to that race as you drive it into the housing.

Arbor press

The arbor press is one of the best means of mounting bearings and races .Its action is rapid and pressure can be applied continuously. During bearing installation be sure to support the inner race with two flat bars placed between the inner race and the press’s adaptor plate. Special precautions should be taken when using the arbor press to align the race squarely on the shaft. Too much pressure exerted by the press could easily cause the race to crack or the shaft to become severely scored. Accessory equipment such as drive plates, tubing or pipes, which will carry the force through the press-fit race, should be used whenever possible

Drivers

Drivers may be used for assembling cups, cones and tapered roller bearings. Drivers assure easier assembly by straightening the cups or cones. They also will prevent damage to bearing cages and internal parts  To use the driver method, first separate the cup from the cone. Apply pressure to the races only, and drive each into position. Be careful not to hit the cage. Pressure against the cage will distort and loosen it, causing slanting of the rollers and premature bearing failure. Never use hammers or drift pins directly on the surface of the bearing. If a hammer must be used to mount the bearing, apply pressure to a drive block, adapter sleeve, pipe or tube placed above the bearing. Direct blows to the bearing can cause cocking, denting, cracking and bearing failure

Clutch release bearing: a special mounting procedure

The procedure for mounting a clutch release bearing onto a carrier or sleeve that will be installed in a vehicle is somewhat different from other installation methods. First, lubricate the bearing shoulder on the carrier with a few drops of oil. Place the bearing on a clean drill press table, with the clutch finger face down. Be sure all parts are square. Start the bearing carrier or sleeve into the bore of the bearing by hand. Shift the drill press into the lowest available spindle speed, and close the chuck completely without the drill bit installed. While the spindle is turning, feed the chuck into the bore of the bearing carrier or sleeve until the bearing is completely seated If the chuck diameter is too small or too large, use a small shanked pilot clamped in the chuck to seat

the bearing. Finally, pack the carrier or sleeve with grease before installing

it in the vehicle.

Installation checklist

1. Work only with clean tools, clean hands and clean surroundings to avoid damage to the bearing.

2. Shaft seat and housing bore should be clean, smooth, with the correct dimensions.

3. Leave bearings in the package until ready for assembly. Do not wash off the lubricant covering them.

4. Lubricate the race being press-fit, and shaft or housing seat on which it will sit.

5. Start the bearing on the shaft with the rounded corner of the race going on first.

6. Apply even, driving pressure directly only to the race being press-fit. Be sure that pressure is straight and square.

7. Never hammer directly on races or rollers. Do not use a wooden or soft metal mallet, as chips or splinters may enter the bearing.

8. Use smart, quick taps rather than heavy ones.

9. Be sure all driving accessories and fixtures have straight, square ends.

10. Drive races solidly up against the shoulder of the shaft and housing.

11. Pre-lube bearing prior to installation