What is a connecting rod? It is the element of the engine responsible for transmitting the pressure of the gases that act on the piston to the crankshaft. Or what is the same, it is a link in the chain that transforms the alternating displacement of the pistons into the rotation of the crankshaft.
As you can imagine, the efforts they have to endure connecting rods and other engine components they are very talland engine block or cylinder head. Thus they can move a car of one, two or even more tons. In addition, the connecting rods are a difficult element to lubricate, that is why they are a critical part of the engine and its design y manufacturing They are very important.
Parts of a connecting rod
foot (small ring)
The connecting rod is divided into three parts, the first is the foot, which is the end that is attached to the piston. To anchor and receive proper lubrication at the same time, you need several components:
- Shell: goes inside the hole in the bottom of the connecting rod. It has holes for the oil to enter and lubricate the area well.
- tube or cylinder: cross the piston, which has two holes in the body, and the foot of the connecting rod (which is housed inside the piston below). It is only in contact with the connecting rod bushing because, as we told you before, it is placed in the foot hole. This tube can also be called a bolt.
Body (bar that joins both rings)
The body is the connecting rod center area, which must support most of the efforts, but being in continuous movement must also be light. They are usually built with a section in the form of a double T or H in the engine types high perfomance. Although in more conventional engines they can also be built in the form of I.
La section refers to the shape that could be seen in the body of the connecting rod if I divided it in half and looked at the cut. If it's a H, means that its edges are wider to maximize its resistance and the center is finer, to lighten it. If it's shaped like I, means that it is the same width everywhere, because it does not need the extra strength of thick edges.
connecting rod head (big ring)
The head is the part that goes attached to the crankshaft and that therefore is the widest hole. Unlike the foot, the head splits into two halves, one of them is the extension of the body, and the other is joined to the other by means of two screws. An arrangement that allows its easy disassembly.
- Bonnet: connecting rod big end removable half
- Bolts: screws that join the cap
- Shell: metal cylinder that is pressed into the big end of the connecting rod. It has some small holes through which the oil enters to lubricate it because it is what is in contact with the crankshaft that is going to rotate. Also called bearing or bearing.
types of connecting rods
As a connecting rod is not an exclusive element of the automotive industry, there are many types depending on the needs of each machine. However, if we talk about vehicles with a combustion engine, there are some types of special connecting rods, that differ slightly from the description we have given you so far:
one piece connecting rod
They are the ones with the head made in one piece, instead of two bolted together. Therefore, to remove them, the engine must have another alternative decoupling system. For example, let it be the crankshaft that can be broken down into parts. Normally in the crankpins, which is where the connecting rods are attached.
oil drip rod
They are connecting rods that have a point through which the oil drips. It is a way of directing and having greater control of the fall of the oil once it has passed through all the components that needed lubrication.
lightened connecting rod
The technical description of this type of connecting rod is somewhat dry: “It is a lightened connecting rod if the plane that divides the connecting rod head into two halves and the plane that passes through the axes of the foot and head (median plane), They do not form a right angle. In the picture you can clearly see what this refers to.
'Fork-and-blade' cranks
these connecting rods they go in pairs and hooked to the same crankshaft journal. One of them has two heads and the other has only one that is inserted between them, in such a way that they make a set similar to a hinge or a two-pronged fork and a knife inserted between them. The cap goes inside the hole formed by the three heads.
Many times, to attach two connecting rods to the same crankpin, simply use two single connecting rods side by side. In such a way that only a slightly longer crankpin is needed to fit both. In the following video you can see how is the solution used in the V8 and V12 engines of the animations.
articulated connecting rod
Depending on the configuration you may need your cranks to have more than one hole in the heads. This way they can receive the movement of two or more connecting rods. This is the case of the connecting rods master and slave in which there is a main connecting rod and one or more connected to smaller secondary holes.
The number of slave connecting rods can be very high. For example, those who use a radial engine Like some airplanes. Although there are also motors of this type in which there is no master connecting rod and all the slave connecting rods are connected to a disk with holes arranged in a circle.
Another special example of articulated connecting rods are those used by motors. Nissan VC-Turbo. In order to vary the compression ratio at any given time, your connecting rods have one body anchored on one side and another body on the other. This way they can make a rocker play that pushes the piston higher or lower as needed inside the cylinder or cylinder. the shirts. In the video below you can see them in action.
There are also types of connecting rods with special properties, as are the patented by Toyota for your variable compression engine. In this case, the connecting rod has hydraulic pistons that vary its length.
Materials for making connecting rods
Connecting rods are usually made of forged hardened steel, although in high performance engines connecting rods of some aluminum alloy or even titanium are usually used. To give them the final finish that you see in the images, machining is usually used (machining in some Latin American countries). Which consists of carving the precise shapes that are needed.
The connecting rods titanium and some aluminum alloys, are usually manufactured directly with the machining process, since the forging method can be somewhat more complicated with these materials. Which makes its manufacture more expensive, beyond the price of these materials, which are already more expensive.
connecting rod function
As we have told you, the connecting rod is what allows the passage of the upward and downward movement of the piston to the circular movement of the crankshaft. What is nothing more than operating principle of the connecting rod / crank mechanism, which already used steam engines long before.
For those who are not familiar with the components we have mentioned, you can make a comparison to running a bicycle. Actually, when riding a bike, movements are made that are very similar to those of a motor. The cyclist is the one that contributes the force in a similar way to the pistons, which are pushed down by the gases of the engine. The cyclist's legs are the equivalent of the cranks that we talk about in this article. Finally, the pedals of the bicycle are the crankshaft that move these legs.
Engines without connecting rods
There are internal combustion engines without connecting rods, as is the case of INNEngine motor, which you can see in the video. In it, the conversion of the alternating movement of the pistons is converted into rotation movement thanks to some cam plates. The pistons have wheels that slide down the ramps of these plates, forcing them to rotate.
Also exist free piston engines, which function as a two-stroke engine but in which the movement of the piston up and down is produced only by gas pressure. They were originally used for the compression of air or any other gas, but over time various car gears have been added to the development of free piston engines to move vehicles or charge batteries.
General Motor and Ford were the first to invest resources in this type of engine (in the 40s) and in 2104 it was Toyota that opted for them to be used as generators. Its main advantage is they have far fewer moving parts, which greatly facilitates its manufacture and maintenance.
Between the connecting rod and the crankshaft there are some pieces that, according to what I have heard, are called tiles. That's the correct name?
regards
it's called bearings! These serve to prevent friction between metal and metal and also serve to prevent heating of these parts.
not its mechanical term is bearings
simon these should not be sanded because they have an exact measurement for the synchronization of the crankshaft with the connecting rod
Boy, I need to know what tiles are for the motor, I already killed myself looking for that and I can't find it, too, that they are axial for the motor, someone help me please, it's a job I'm doing. first of all, Thanks
yes pz I'm studying automotive mechanics and I'm watching videos of the connecting rod
tiles, shells, caps but its technical term is bearings, which is the part that has the numbering, the technical term is the bearing.
Good with the info. Thank you
I have read that the head of the connecting rod is also called the connecting rod ring…and that the foot of the connecting rod is called the connecting rod eye…is it by chance also a name that is given to it???… thank you very much in advance….
Cheers…. 🙂
what is squaring cranks?
hello very good document
all those who wrote those stupid things are gonorrhea fidos bengan and dogs suck me
How many holes should the connecting rod bushing have, iron has three, but should the bushing have the same?
IT IS COOL TO STUDY THE ENGINE PARTS
IT IS COOL TO STUDY THE ENGINE PARTS
Who can tell me some characteristics of the connecting rod?
Where it says (it is attached to the crankshaft) I think it should say that (it is attached to the pin or piston pin) which would be the first part of the division of the connecting rod, that is, the connecting rod foot
what a chebret
hello, the crank has a mark where that mark goes to the front of the engine or to the side of the exhaust pipe grace
I need a bi3la for a mitsubishi endeavor2004 could you give me an idea where I can find it
Hi... which crank is better aluminum or titanium???
They tell me that to change the metals of the crank you have to open the engine? It's true
Well, I would like to know what the connecting rod horns are made of and how the connecting rod horns are disassembled, I hope you can help me for my exam
where can i get 2 connecting rods for a toyota camry 2004 engine 2.4
I have toyota camry engine spare parts if you still need them write me.
the connecting rod is gripping the crankshaft and the piton and the construction material must be very strong, the tiles that they tell you are the connecting rod bushings, any information call or whatsaap 50496117609
Function of the connecting rod is?
Does anyone know how to identify the thickness (size) of a connecting rod shell. is there any code?
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this is useless
The connecting rod has the function of turning the crankshaft thanks to the 4-stroke engine. the connecting rod inside the head part has another metal called crankshaft bearings that prevents metal from rubbing against metal but at the same time that bearing is lubricated by oil that enters through holes in the crankshaft.
Hello, I would like to know if placing an inverted connecting rod causes excess fuel in the exhaust.
THE PAGE IS VERY GOOD. I AM STUDYING AUTOMOTIVE MECHANICS AND YOU WILL LEARN A LOT THROUGH THIS PAGE.
Who can help me? I'm worried. I left on my motorcycle on my way to work, which is about an hour away because it happened that on the way I made a mistake, VAT in 4 gears, and I was going to put in 5 gears, but since I was able to put it in very well, I stayed in black the board had neither fourth nor fifth as it had remained in neutral and I thought that I had put fifth I hit the acceleration but no way because the change had entered well but the acceleration was very strong it could be that it could have damaged the connecting rod or something because the engine revved up a lot on nothing would happen friends
Hello..I have a concern. ..I disassembled a thousand cars..A dodge 1500 model 75…And I see that the measurement of one of the pistons is 0,35 ..some mechanics tell me that the cylinders are no longer rectified. ..Others that he has one more left. ..How could I know? What measurement should I take to recognize with the caliber to know? I know that it should be measured with an alesometer but I do not have that tool. .Just gauge. .Thank you
this didn't work for me -_-
HOW MANY KILOS OF TORQUE DOES THE CONNECTING ROD OF THE DODGE 100 MOTOR VALIANT ??????????
I have a Mitsubishi car older than 94. I am buying the connecting rod and main shells. But they ask me if they are thin or thick? What type does that 6g63 engine use? The signal was rectified and remained at 010
Well, I don't know if I'm wrong, but the foot is the smallest, it goes with the bolt and is hooked to the piston, NOT TO THE "CRANKSHAFT"
You can change a connecting rod head for another connecting rod head