Structural characteristics of Cam followers, adjustment and maintenance of axial clearance

CAM follower is a kind of thick outer ring needle roller bearing and bolt combination structure of bearing; The bolt of the bearing is provided with a lubricating oil channel; The outer surface of the outer ring has cylindrical shape and spherical shape, which can be selected according to the actual application; When installing bearings, it is convenient and accurate to adjust the axial position of bolts, generally used in automobile camshaft (the shaft that controls the opening and closing of piston engine valves).

Structural features of Cam followers

1. Thick outer ring needle roller bearing and bolt combination structure 2. Sizes include metric series and inch series
2. There is a lubricating oil channel in the bolt of the bearing
3. In order to facilitate installation, the big end of the bearing is designed with “word type” and “hexagonal hole type” wrench assembly method
4. The outer surface of the outer ring has cylindrical shape and spherical shape, which can be selected according to the actual application.
5. Full roll type is suitable for occasions with large load and low speed
6. The eccentric type can easily and accurately adjust the shaft position of the bolt when installing the bearing

CAM follower series

CFxx standard

CFxxF stainless steel version

CFESxx solid eccentric bolt type

CFExx eccentric

CFxxW thrust disc

CFxxRUI concentrated lubrication spherical outer ring

CFxxFUI concentrated lubrication cylindrical outer ring

Simple assembly of CFxxSFU

NUCFxx heavy

CFSxx small

CRxx – x standard

CRHxx -x heavy type

How do you protect CAM’s fans

1. The newly put into use vane CAM pump generally needs to replace the grease (oil) after 100 hours of operation, and then every 500 hours of operation.
2. The flow bearing lubricated by grease should be replaced after 1500 hours of operation. The amount of oil should not be too much or too little, because too much or too little oil will make the bearing hot. The oil quantity is generally controlled in 2/1—-2/3 bearing cavity volume is appropriate.
3. For bearings lubricated with lubricating oil, a certain amount of oil should be added at the specified position.
4. The container containing lubricating oil or grease should be clean, usually well sealed, no dust, iron filings and other debris, so as not to damage the bearing.
5. Motor bearings are made of Nami-based grease, which is characterized by high temperature resistance (125°C), but easily soluble in water, so it can not be used for lubrication of water pump bearings.

Camshaft axial clearance adjustment

The axial clearance of camshaft should comply with the relevant regulations. The inspection method is shown in the attached picture. The thickness difference between thrust flange and gasket is measured with a thickness meter or directly. When thrust flanges wear out the shaft

When the direction gap exceeds the specification, the thrust flange of standard thickness should be replaced, and the thickness of gasket can not be arbitrarily reduced, otherwise it will change the axial position of the CAM, affecting the accuracy of the valve phase.

How to repair the camshaft and its bearing

When checking the axial clearance of the engine with thrust flange, insert the feeler between the front end face of the first shaft neck of the camshaft and the thrust flange or between the end face of the hub of the timing gear and the thrust flange. The thickness of the feeler is the axial clearance of the camshaft. Generally 0.10mm, the use limit is 0.25mm, such as the gap does not meet the requirements, can be adjusted by increasing or decreasing the thickness of the thrust flange.

The bending deformation of camshaft is measured by the radial circular runout error between the middle and two ends of camshaft journals. Place the camshaft on the V iron and the V iron and dial gauge on the plate so that the dial gauge contact is in vertical contact with the camshaft middle journal. Turn the camshaft, observe the dial gauge needle pendulum difference is camshaft bending. After the inspection, the inspection results will be compared with the standard value to determine whether to repair or replace.

Camshaft other maintenance items

1. Overhaul of the keyway of the timing gear shaft neck: the symmetric plane of the keyway of the timing gear shaft neck should generally coincide with the symmetric plane of the maximum lift of the inlet and exhaust CAM of the first cylinder, and its wear will change the timing of the valve. When the keyway is worn, it can be rewelded or another keyway can be made in a new position.

2, gasoline pump driving eccentric wheel limit wear: gasoline pump driving eccentric wheel limit wear is generally 1㎜, more than the limit should be replaced camshaft.

Static jump value: standard – 0.01 ~ 0.03㎜, limit – 0.05 ~ 0.10㎜.

The bending deformation of camshaft can be repaired by cold pressure correction, but it is better to replace new parts.

The wear of the CAM changes the rule of valve lift and decreases the maximum lift, so the decrease of the maximum lift of the CAM is the main basis for the classification of the CAM.

If the maximum CAM lift decrease is greater than 0.40mm or the cumulative wear of the CAM surface is greater than 0.80mm, then replace buxic  the camshaft; If the cumulative wear of the CAM surface is less than 0.80mm, replace the camshaft grinder.