Car tappet: the principle of operation and device

These details was included in the design of the car recently. In the 60s they began to pick some model cars. The device and principle of operation of the tappet interesting to many drivers, and so, we need to talk about them.

What's he doing?

When the motor is wound up, all the details in his design are heated to high enough temperatures. More from school physics course we all know that when heated body expands. In order to avoid damage, reviled wear of individual parts, the whole engine there are special thermal gaps. When the engine is warmed up, they are absorbed as a result of increases of certain items. But as soon as the knots are worn, the size of them when heated, are unable to absorb the thermal gap. It's not the best way affects the dynamic and other characteristics of power units.

Why the tappet in the car

Heat clearance in the valve mechanism greatly affects the quality of work, and generally on the performance of the engine. Due to the natural wear of the valves are constantly changing. At the very beginning of the history of the internal combustion engine these gaps are regulated by means of ordinary wrench. This process required a regularity that would significantly increase the complexity and cost for this procedure.

So the engineers, to make life easier for motorists, has developed a tappet. The principle of operation consists in absorption of the clearances between the working parts of the camshaft and between the rockers, rocker arms, valves and rods. In this case, the compensation should not depend on the temperature or degree of wear of parts and assemblies.

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Types of lifters

To Set these nodes can be any type of timing mechanisms. Depending on what design the timing, there are four basic types of lifters. This is the tappets, gidropony to levers or rocker arms and roller followers.

Despite the fact that the design of the mechanisms are different, the principle of operation of the same. They are all intended to compensate for gaps between the valve tappets and camshafts.

For example, the principle of operation of hydraulic lifters for "Chevrolet" in that instead of the traditional regulatory clearances in the cylinder head screws are now used piston pair. To these couples from the lubrication system enters the hydraulic working fluid. This causes the lever all the time to cuddle up to the Cam of the camshaft. With such devices there is no need for clearance adjustment.

The history of the creation of this mechanism

It is Known that the first car that manned these small nodes is the "Cadillac 452". It was collected in 1930. As the power unit used V16. About the convenience of maintenance and repair of the car then still wonder why the tappet, the principle of it was invented much later. So, there is information, the popularity of these mechanisms came in the 80s when the market was full of Japanese cars.

How does the tappet

Among the main parts of this mechanism can identify a body, plunger pair, spring and check valve. As for the case (and the case can be different depending on the design of the actuator) may be cylindrical tappets, rocker arm, or part of a cylinder head.

The Principle of operation of the tappet cars built on the plunger pair. She, in turn, consists of a sleeve, which allows the plunger to move in a certain direction. Also in the design include a plunger. It is a steel cylinder, which is in the lower part has a hole. This hole connects the cavity inside the part and under it.

Some designs where there is a track single boom Dril lever, provide for the plungers without internal cavities. The plunger spring is retained between the plunger and the bushing. As a non-return valve using a steel ball with a spring.

The Principle of operation of the tappet valves

So. In that moment, when the camshaft lobe is relative to pusher her backwards, he did not shrink. While the engine is cold, between the Cam and tappet gaps exist. A spring in the application of force it will start to push the plunger up until the distance disappears completely. Along with this, the oil from the lubrication system of the car is transmitted through a spring loaded valve with a ball in the internal cavity of the compensator.

With the turning of the camshaft, the Cam presses on the pusher housing. Thus, the casing pressure is moving down, closing the lubricant channels. The ball valve is closed, and the pressure of hydraulic fluid under the plunger increases. So as to squeeze the liquid is impossible, the pair works on the principle of rigid support and force of the Cam is transmitted to the valve stem. By the way, this principle of operation of the hydraulic "priors" great show.

Though the gap, which is in the plunger pair is only 0.8 microns, the oil is still in a small amount goes through the process the cavity between the plunger and the bushing. Thus, the pusher is slightly lowered. The size of drawdowns may depend on the number of revolutions of the crankshaft. For increased speed reduces the level of leakage of hydraulic fluid from beneath the plunger.

Gap (the moment when the camshaft lobe comes off the tappet) kompensiruet through the power of the return spring and oil pressure. The principle of operation of the tappet auto helps to ensure that no unnecessary space between items. This has been achieved through rigid links between nodes of gas-distribution mechanism. When the engine heats up, the dimensions of the parts of the compensator are also changing, but these changes kompensiruet almost instantly.

Advantages and disadvantages

The Use of these mechanisms has enabled motorists to avoid the procedure of adjusting the valve clearances manually. In addition, the engine has become more soft. Significantly decreased impact load, which allowed to extend the resource details of timing and to reduce noise effects during operation of the unit. The tappet, the principle of operation it also allowed us to more accurately coordinate the timing of the phases of gas distribution. This is the best way affected the safety of power units, power, dynamics and fuel consumption.

Among the disadvantages emit poor quality and noisy cold start of the engine. In the first few seconds the oil pressure has not yet reached the desired level, so the expansion joints can be a little knock. This is true even on foreign cars, because the principle of operation of hydraulic “great Ox" is little different from domestic developments.

Causes of output failure details

Despite the simplicity of construction, these nodes also fail. In most cases, the most popular reason – it's a dirty oil passages of the motor. Or strong wear of the working parts of the valve return stroke. Contamination can arise from use of improper oil, the replacement is not performed on time or the failure of the oil filter.

If increased landing clearance piston steam, process oil leakage may increase. Lose the rigidity, with which the tappet, the principle of it is that the oil pressure should be required. The same thing happens, if badly worn out check valve in the high pressure chamber.

Inside the tappet must be filled with lubricating hydraulic fluid. If in the cavity there is air, then the gaps will not be reimbursed fully, if not will not. In this case, can help to repair the lifters. The repair can be required in case detail stuck in mechanism to catch any foreign particles.

How to avoid it?

You Should keep clean the inside of the engine. It is recommended that regular replacement of lubricants and filters at the manufacturer's recommended time. You should also regularly clean the motor before replacing the grease. Need to know what small gaps in wagramerstre require very high quality oils. You can use a synthetic or semi-synthetic oil of medium viscosity.

Diagnosis and repair of hydraulic lifters

To Diagnose the broken element by a characteristic knock. Then a suspicious mechanism to remove and visually inspect for wear and damage. If the item is dirty, wash it in acetone.

To work properly, there is a special additive for the lifters. The tool allows to eliminate the causes of the noise mechanism at work, and also effectively cleans the item.