The crank shaft is the force that makes the whole rod-crank crank. Its function is to transform rotational movements in alternative movements (combustion engines, for example) or vice versa (Eccentric mechanical presses).
In the heat engine crankshaft collects forces originated during the explosion and turns through the rod, linear motion into rotary motion of the piston alternative. Transmits the movement and the driving force transmission elements that are coupled. Is subjected to bending and torsion efforts, and has a strong structure and very resistant. The crankshafts, which can be obtained through melt processes or wrought alloys are made of steel with Cr, Ni, Mo, etc. It consists of some supports, normally five for a four-cylinder engine, which are subject to bench the block. It also carries some elbows called stumps where the rods are held. The extension of each side are the counterweights used to balance the crankshaft. At one end of the crankshaft mounted pinion distribution, and on the other, the flywheel.
The heat engines are examples of engines that use a crank to turn the movement into alternative movement of rotation. The eccentric mechanical presses, however, are examples of mechanisms used to turn the crankshaft rotational movements in alternative movements.
Operation of the crankshaft
In looms crankshaft also called colzet. The crankshaft has a crank for each side of the machine or engine. The side receives the crank on the stump, which revolves around the offset axis of rotation of the crankshaft. The stump which constitutes the axis of rotation of the crankshaft is supported by the neck or bench. The arm is the part that connects the crankshaft stump and neck. There are usually one arm on each side and a neck stump for each arm. However there crankshafts compressors have only a neck, arm and stump and crankshafts Engine light of two, four or six cylinders that have stumps grouped in pairs, with one arm intermediate single and without neck between two consecutive stumps.
To offset the effects of imbalance caused by decentered rotation of the stump and the crank arm at the end opposite the balances settled there a stump. These balances can be a single piece with the crankshaft or may be bolted heavily on arms. Crankshafts in more than one side, there is Talma elbows, the masses of decentralized elbow compensate the masses decentered another in order to get a better balancing.
This provision elbows cylinder determines the succession of explosions and the whole distribution. The crankshafts are obtained by forging and subsequent machining, or from one piece necks, arms and stumps apart and mounted coupling pressure hot to allow the mounting of bearings or roller on the stump . The same technique applies to very large crankshafts, marine engine, for example, to avoid the difficulty of obtaining heavy forgings or castings too.
The engine crankshaft is the part that has to bear the greatest efforts of fatigue and wear. In aircraft engines, or engines where the conditions of weight, safety, freight are severe hardening heat treatment and surface nitriding, flame hardening or induction hardening are widespread.
The crankshaft can be of two types:
- Composite / separable, these trees are separable in that the pin which houses the head of the connecting rod can slide in order to accommodate the connecting rod with the head in one piece and its support to improve reliability and reduce dispersion media to friction, however, this type of construction is very difficult to achieve, given the many factors that must be respected to avoid falling into vibrations; so its use in civilian vehicles generally united by the engine with two cylinders possible.
- Monolithic, these trees are among the most used, because it allows a more whole and may have small underweight models separable from the fact that consist of a single item.
In addition, depending on the characteristics of the engine can be simple when using a single motor shaft to the motor, multiple, when there is the need for more trees may also be needed more trees per cylinder engine, as in the If engine crankshafts trees or DUA opposed piston, which have two axles rotate in the opposite direction to the piston to minimize lateral forces the piston.
Last review: November 18, 2016Back