The piston finger is the part that provides the moving connection of the Jackass and the piston. It is a piece of cylindrical shape that is remotely similar to a finger. Use of reciprocating finger

Use of reciprocating finger

The piston finger connects the piston to the Jacket. The connection between these two parts cannot be hard, as the bottom and top of the jackass are continually moving. The cylindrical finger allows the upper part of the jacker to "loose" when the piston is moved vertically.

For mounting the floating finger, the piston and the finger are boiling hot in the hot water

Why is it hard to make it easy?

The primary task of designers of modern engines is to increase the power and, at the same time, reduce the weight of the engine. In order to reduce the weight of the entire aggregate, it is necessary to facilitate the details by any available means.

It is not easy to make a piston finger easy, as this detail is constantly under severe strain. Light and durable alloys that can be used to produce piston fingers are expensive and the cost of the product is significantly increased. As a result, most modern engines use fingers of alloy steel, just as they were a century ago.

Why is there a hole in the centre of the reciprocating finger?

Usually there is a hole in the body of the finger in the form of two cones with vertices in the center. The hole can reduce the weight of the part and the conical form is connected to the distribution of the load on the surface of the part. The centre of the finger is much larger, and at this point the thickness of the material plays the most important role.

Finger-finger Axis Modes

Fingers are divided into two kinds: floating and fixed. Most modern engines use floating fingers.  The floating is called because there is a gap between it and the hole in the piston and the hole in the head. The fixation of the piston finger in this connection shall be ensured by the installation of hard rings.

Colored labels inside the finger holes of some vehicles replace the spare parts for the parts for the engine's motors

Finger

The floating finger can be rotated both inside the piston and in the head of the Jackass. In the floating-finger constructions, a bronze-tulking tuller is pressed into the upper head of the jackass.

Since the jackass, piston and finger are made of different materials, the gaps in the connections are calibrated according to the properties of the metals. For example, at room temperature, the finger should be included in the tuft of the tumour without any play. The piston hole (at room temperature) must pass with some thrust.

Mounting of the Wrath Finger

When mounting or removing the piston, it must be heated to a temperature of 65-85 ° C (heating in water). When the engine starts working, the piston is warmed up and the gap widens, as the piston and finger are made of different materials, which are spread differently under the influence of high temperature.

To mount a fixed finger the jackatun is warmed up to a temperature of more than 200 degrees

Finger

A fixed name is a piston finger that is not rotating in any of the connectable elements. The fixed fingers are used in the engines of cars of the VAZ family.

fixed finger mounting

The fixed finger is fixed by heating the jackass to a temperature of 240 ° C in the oven. In Russia, where cars are still often repaired at home, shatunas are often heated on home electric tiles or with a torch.

The shatun is getting cold, and the operation to connect the piston finger and the jacker is very fast.

In order to do this, in the pushed advance sponges, insert of soft metal (aluminium, copper, etc.) shall be installed, and the heater is quickly moved to the vice and clamps. The piston shall be mounted with the hand.  The finger, which is prepared to be put on a special line with the guide, is pushed into the piston hole and passes through the hole in the hot swoon. When the details get cold, the hole in the cap is pressed against the finger.

Fingerprint

If a floating finger is used in the engine, it is selected in the colour label that is applied inside the bottom of the piston, or by a catalogue number. Porshns and piston fingers are divided into size groups, depending on the diameter, which should be kept in mind when purchasing details.

When you select a fixed finger, the finger is picked up by the piston hole in the group number specified on the bottom of the piston.

Fingerprint material

The main steel for piston fingers is 45HA. When the details are cast, the part is filled to 1-1.5 mm of depth. The hardness of the surface shall be in accordance with certain standards. In high power motors, finer gradations of alloy steel are used for the production of fingers.




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