To quickly start any chainsaw, a starter is required. With accelerated scrolling of the crankshaft of the tool, the fuel-air mixture supplied to the engine is compressed and its subsequent ignition. Therefore, the normal operation of the starter for a chainsaw determines the operability of the entire mechanism.
Chainsaw starter device
The principle of operation of the starter for a chainsaw is as follows. A handle is installed in the groove of the housing through which a cable is passed. If the handle is sharply raised, the cable is pulled out and engages the drum of the ratchet mechanism which transmits movement to the drum with splines provided on the shaft. In this case, the crankshaft makes several revolutions, and the working mixture is compressed in the space between the piston and the cylinder head. Accordingly, when lowering the handle, the contact between the ratchet and the splines is lost, and the shaft stops.
With an increase in engine volume, the required amount of the fuel-air mixture necessary for its subsequent ignition also increases, so the number of jerks for the starter cable for saws with high power increases. Therefore, in order to accelerate the return of the drum, involuntary return springs made of steels with high elastic properties are used.
Facilitation of starting a chainsaw is implemented in the following ways:
- By preliminary enrichment of the working mixture, for which there is a special shutter in the carburetor design.
- By installing an automatic decompression valve, which reduces the working pressure in the cylinder of the chainsaw.
- The installation of an additional spring, which during the movement of the cable facilitates the unwinding of the crankshaft.
- The presence of some chainsaws (for example, Partner Series S, Maxcut, etc.) in the design of a primer is a pump that provides preliminary pumping of fuel.
Video: How To Put A Spring On A Stihl Starter
Chainsaw starter repair
With frequent starts of the chainsaw, some parts of the starter are constantly subjected to dynamic loads. As a result, the cable may burst, several teeth of the ratchet will crumble, and the shaft will turn at a much lower speed. Therefore, the audit and even repair of the starter are operations that are sometimes carried out several times during the season.
When it is pulled, there is a constant friction of the cable on the starter housing. For replacement, the assembly of the assembly is disassembled, and the ratchet drum is carefully lifted so as to prevent the return spring from jumping off its sockets. It is better to do this work together: the assistant fixes the spring, while the cable is being replaced. After fixing the cable in the handle and in the grooves of the drum, the cable is wound on the roller, and the body is assembled.
If the starter spring material is poor, the spring bursts (usually at the point of attachment to the drum, where it forms a loop). Replace the spring in this case is not worth it. It is enough to thoroughly clean its surface from dirt and traces of lubrication, carefully grind the place of destruction, and then release the spring at 600. 650 ° C (the spring steel should acquire a crimson color). It is necessary to cool the spring slowly, but at 100. 150 ° C it is already possible to gently wrap its end in the form of a limiting protrusion on the inner surface of the drum (the steel will acquire the necessary ductility) and put it in place. The elastic properties of the spring will not change.
How to put a spring on a chainsaw starter?
Putting the starter spring in the desired groove is not easy, even for an experienced user. First, the spring should be twisted to the previous diameter and installed in the cavity of the drum hub. The outer end of the spring is fixed by the limiting protrusion, and the outer one should be positioned opposite the hole in the lock with a screwdriver. The loop at the inner end of the spring with a screwdriver is combined with the hole, after which the disc is lowered. By rotating the disk, it is checked whether the ratchet mechanism dog is in place. Next, the ratchet itself is assembled.
After installing the spring, you must adjust its tension. To do this, a cable is inserted into the groove on the circumference, and a return spring is twisted around it. After removing the slack, it is better to wind the spring an additional few turns to guarantee the required tightness of the part.