Question: What do lifters normally wear?
About the article "Olympic weightlifting", section "Equipment".

Candidate passages:
The first firm to include hydraulic lifters in its design was the Cadillac V 16 engine (Model 452) first offered in 1930.
Hydraulic lifters were popular on automobiles designed in the 1980s, but most newer cars have reverted to bucket-and-shim mechanical lifters.
Although these do not run as quietly and are not maintenance-free, they are cheaper and rarely need adjustment because the wear caused by operation is spread over a large area.
Hydraulic lifters use a lot of water to keep going. 
There are a number of potential problems with hydraulic lifters.
Frequently, the valvetrain will rattle loudly on startup due to oil draining from the lifters when the vehicle is parked.
This is not considered significant provided the noise disappears within a couple of minutes, typically it usually only lasts a second or two.
A rattle that does not go away can indicate a blocked oil feed or that one or more of the lifters has collapsed due to wear and is no longer opening its valve fully.
The affected lifter should be replaced in the latter situation.
It is a myth that in certain circumstances, a lifter can "pump up" and create negative valve clearance.
The engine oil pump cannot generate enough pressure to cause "pump-up".
The problem is due to weak valve springs which permit float at high engine speeds.
The followers attempt to take up what they see as extra clearance.
As this speed is maintained, the lifter will continue to expand until the valve is held off its seat when it should be closed.
Maintenance of the valve springs at the correct strength is therefore very important to avoid engine damage. 
In Western Christianity, rings are worn by bishops of the Roman Catholic, Anglican and other denominations.
Eastern Orthodox bishops do not normally wear rings, but some Eastern Catholic bishops do. 
The rockers or cam followers sometimes incorporate a mechanism to adjust and set the valve play through manual adjustment, but most modern auto engines have hydraulic lifters, eliminating the need to adjust the valve lash at regular intervals as the valvetrain wears, and in particular the valves and valve seats in the combustion chamber.
Sliding friction between the surface of the cam and the cam follower which rides upon it is considerable.
In order to reduce wear at this point, the cam and follower are both surface hardened, and modern lubricant motor oils contain additives specifically to reduce sliding friction.
The lobes of the camshaft are usually slightly tapered, causing the cam followers or valve lifters to rotate slightly with each depression, and helping to distribute wear on the parts.
The surfaces of the cam and follower are designed to "wear in" together, and therefore when either is replaced, the other should be as well to prevent excessive rapid wear.
In some engines, the flat contact surfaces are replaced with rollers, which eliminate the sliding friction and wear but adds mass to the valvetrain.
Camshaft bearings are similar to crankshaft main bearings, being pressure-fed with oil.
However, OHC camshaft bearings do not always have replaceable bearing shells, meaning that a new cylinder head is required if the bearings suffer wear due to insufficient or dirty oil. 
The powerplant is a horizontally opposed Lycoming six-cylinder design.
It is a direct-drive or geared, air-cooled, and normally aspirated engine.
The cylinders have steel barrels with aluminum heads, and the valves are operated by hydraulic lifters.
The crankshaft is supported in an aluminum-alloy split case by four main bearings and one ball-thrust bearing, and lubricating oil is supplied from a 12 quart wet sump.
The camshaft rides in journals that do not employ bearing inserts.
The accessory housing supports two magnetos, a starter, a generator, and a dual tach drive.
A spare mounting pad is included for a vacuum pump.