Design and principle of chain saw oil pump
The groove on the shank ensures that the oil from the oil tank of the saw is captured and routed to the hose that feeds it to the bar.
Plunger on brand name saws is made of one solid metal rod. But in cheaper kinds usually the pinion is not only forged but also mounted on the ramrod, which of course affects the service life of the part.
The groove on the end is of several kinds:
- There is a ½ to 1/3 of the plunger diameter longitudinal groove on the body for oil catching;
- Radial groove on the end allows for adjustment of plunger movement relative to the axis.
When replacing the oil pump it is important to choose all parts of this particular series of chainsaws to match all protrusions and grooves with the body and adjusting eccentric as closely as possible.
Principle of the oil pump
The vast majority of imported and domestically made chainsaws have a valve-less oil pump located on the crankcase on the chain side. The segmented notch on the cylindrical surface and the plunger rotation from the drive shaft through the worm gearing ensure the supply of lubricating oil to the guide bar.
As the chainsaw oil pump drive rotates, the plunger first launches oil into the discharge chamber, and after rotating 90°, it closes the inlet port and pushes the lubricating fluid out with reciprocating motions. In order to give one axial movement per revolution, an eccentric mechanism is mounted on the end of the plunger, which operates according to the principle of a car camshaft. The axial stroke of the shaft is limited by an annular projection with a profiled configuration.
Breakdown types
Most chain saw breaks down because of wear and tear on the moving parts or for reasons that have to be dealt with on site. Before proceeding with the repair, it is important to properly diagnose the causes of the resulting malfunction, which can be divided into the following groups:
- Failure of the weakest link of the structure (this may be the engine or the chainsaw clutch);
- Damage to a number of ancillary components (brake or chain lubrication system);
- Unintentional failure or deformation of some parts of the chain saw (handle, bar or sprocket).
Depending on the group into which the fault is identified, an appropriate approach to repairing the damaged mechanism will be chosen.
Engine malfunction can be traced to several causes, including failure of the chainsaw’s electronic ignition circuitry and malfunctions in the fuel supply system components. Repair may also be necessary in case of malfunction of the chainsaw piston group.
The basic breakdowns of the oil pump
The oil pump consists of several parts connected in one piece, namely the housing, the oil reservoir, the hose and the gasket between the two parts of the device. The gasket is the most vulnerable part, it becomes deformed over time or if the chain saw is used incorrectly and starts to leak oil.
If the gasket leaks, some of the oil will escape through the gap and much less lubricant will flow to the chain. It increases wear on the chain and guide bar, which can cause them to fail in the future.
Also at risk are the hoses and connectors of the oil pump, which can become clogged with prolonged use, causing the oil pressure to drop. Also affected are the holes where oil enters the guide bar.
The main oil pump failures
The oil pump is made up of several parts that are knitted into one piece, that is to say, the housing, the oil reservoir, the hose and the gasket between the two parts of the device. The most vulnerable place is the gasket, which over time or improper use of the chainsaw deforms and begins to leak lubricant.
Due to a leaking gasket, some oil leaks out through the gap, causing the chain to receive much less lubrication. This increases wear and tear on the chain and guide bar, which can cause them to fail in the future.
Also at risk are the hoses and connectors of the oil pump, which can get clogged with prolonged use, causing the oil pressure to drop. Also affected are the holes where oil gets into the guide bar.
The oil pump on the chain saw does not work
Elimination of oil pump defects: chainsaw repair
Continuous chain saw use can cause parts to fail. In the majority of cases a chainsaw oil pump repair is needed. It is explained by the fact that in the process of sawing there is a huge amount of shavings, which can get into the working mechanism.
Fixing oil leaks
Many saw models have oil pump malfunctions in the course of their operation. The nature of these defects can vary, but in the end it leads to oil leakage. over, such leaks can occur even when the saw is in the prone position. Oil pump; as a rule, an oil pump consists of two on the surface should not. Only the pump itself should not leave an oil slick, even in winter.т.е. Engine running. Justified by the uneven distribution of water in the storage tank.
Leaks are also due to the chainsaw oil pump having a fitting on its own housing for attaching a hose. Failure to tighten the connection between the water tank and the pump can lead to oily droplets.
Design of the lubrication system
Depending on the chainsaw brand, the parts of the lubrication system may vary slightly in design, but their overall number and connection scheme remains the same.
The main components of the lubrication system are:
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oil tank, usually located in the engine crankcase.
principle of operation
The pump is the main component in the system. Its working principle is as follows. As the engine speed increases, the pinion mounted on the main shaft drives the pump shaft through a worm gear. In turn, the rotation of the shaft creates a certain pressure in the oil line, which forces the oil to move through it towards the bar.
The oil channel end is located where the guide bar contacts the tool casing and has a longitudinal groove on which the oil channel flows when the guide bar is installed.
The groove is necessary to ensure the oil flow to the guide bar regardless of the tension of the chainsaw chain. To put it simply, whichever position the tire is in when in operation, the oil will flow into the tyre via the groove.
The lubrication process then involves the chain that, depending on the chain model, has either a groove or a hole in the chain links that allows the oil to disperse over the bar. With increasing engine speed, the oil flow rate also increases.
Some chainsaw models are equipped with pumps, which have an additional flow regulation, and if necessary, the amount of oil fed by the lubrication system, can be increased or decreased.
This function is very useful because it allows the pump to rotate at higher speeds. к. saves oil and doesn’t waste any extra oil.
Principle of operation
The main unit of the system. the pump. Its working principle is as follows. When the engine speed is increased, the pinion set on the main shaft drives the pump shaft through a worm gear. the rotation of the shaft in turn builds up a certain pressure in the oil gallery, which forces the oil through the oil pipe and into the tire.
The end of the oil channel is where the bar contacts the tool crankcase, where there is a longitudinal groove that the oil channel hits when the bar is installed.
The channel is necessary to provide a flow of oil to the guide bar no matter how tight the chain is. to put it simply, whichever position the tire is in when working, oil will get to it through the groove.
This is followed by the chain which, depending on the chain model, has either a groove or a hole in the chain links whereby the oil is dispensed over the bar. As engine rpm increases, so does the rate of oil flow.
Some chainsaw models are equipped with pumps, which have an additional flow regulation, and if necessary, the amount of oil fed by the lubrication system, you can increase or decrease.
This function is very convenient because. к. saves and does not waste extra oil.
Troubleshooting
If the chain is getting too much oil, not only when the saw is running but also when idling, a manual adjustment should be made (if the pump design makes this possible). This is done by means of a screw that is located on the body near the guide bar, usually on the bottom or side. Tightening the screw reduces the oil flow, loosening the screw reduces the oil flow. If the adjustment does not help, you need to check the serviceability of the pump, and also inspect the busbar. perhaps at its connection to the body there is a gap, through which the oil leaks past the chain.
Read also: Yellow wood screws size table
Lack of oil can be caused by several reasons, each of which has its own solution:
- Oil pump malfunction. As a rule, it lies in an unsuitable gasket. In order to replace it, the pump has to be carefully disassembled so as not to damage its moving parts. A new gasket is then fitted and the pump is reassembled and refitted.
- Oil hose breakage. If the pump gasket is intact, or if its replacement fails, check the hose for leaks. If it is faulty, it needs to be replaced. Otherwise, it is not superfluous to clean it and fix it with sealant.
If the reason is not a broken pump, you need to inspect all the conductive holes and channels for clogs, and if necessary, clean them from foreign objects. You can do this with a blast of compressed air.
Don’t want to mess with your chainsaw, but need to adjust the oil flow? Get help from our experts who will diagnose and repair your chainsaw and, if necessary, make repairs and adjust the lubrication level. Your saw is as good as new!
Husqvarna chainsaw repair 137, 142, 240, 365 with your own hands. video
Chainsaw. An indispensable helper for every real craftsman.
With the advent of the tool its popularity has increased dramatically.
So the Husqvarna 142 chain saw has a lot of features. It is not only widely used in forestry, but also in households.
It’s easy to choose a chainsaw. Therefore, it is best to pay attention to well-known brands, such as Husqvarna. This company manufactures a wide range of such tools. Husqvarna 240 and other models have high quality and functionality. But, unfortunately, even such tools are not immune to failure.
How an oil pump works
Before removing the chainsaw pump, it is important to understand the principle by which it functions. The force generated on the actuator, through a worm-type transmission, passes to the plunger (the force transmits a rotary-type motion). The latter starts to rotate, repeating a reciprocating type motion.
This type of movement is guaranteed because of the specific shape of the plunger, the adjusting screw, its stop-type spring, and the eccentric. When the plunger starts moving backwards the oil flows into the reservoir through a small hole (we see this principle in an ordinary syringe as well).
The forward movement causes the oil to be pushed out through the same orifice. It is not difficult to guess that according to this principle the unit works only because of the tightness created by the rubber sealing collar. The working diagram may not show.
over, this principle only works when the two ports are not opened at the same time. To prevent this from happening, the designers have provided a segmented cutout at the tip of one plunger. During the backward movement, it turns toward the inlet port. This hole closes when forward movement occurs. At the same time the outlet hole is open because the cutout is turned toward the last hole. One turn of the plunger occurs with one reciprocating movement.
At the same time, the manufacturers of the saw basic units can change the stroke of the plunger, which requires an eccentric and an adjusting screw. The first is visually just a cylinder integrated into the body of the adjustment screw. The major axis of this part will not align with the axis of the adjusting screw, even when the screw is rotating.
The cylinder will move in and out of alignment with the ram ribs. This is important to know in order to understand the plunger’s function. This type of displacement of this part is the reason why it became known as the “cam”.
If the plunger comes as close to the cam as possible, oil cannot be pumped. In the opposite case, the plunger will let the oil stroke to the maximum (pump at full power).
Also be sure to take a look at this article on how chainsaw chain lubrication works. The information also relates to the oil and its flow to the working parts.
How the Plunger Moves?
It moves because of a special facing that is centered on the eccentric. The edge of this end resembles a normal ring and is surrounded by a protrusion located in the center. This ring is at an angle, not perpendicular to the plunger axis. By forming a bevel, this part allows the plunger to protrude slightly.
In this case the edge of the plunger and the adjustment screw are connected in a specific way. It allows the face to touch the screw during movement with different parts, protruding and not protruding. When the flange touches the screw with its protruding part, the plunger rotates forward. When the rising edge touches the adjusting screw with a non-rotating part, it rotates backward. Backward movement is possible due to the stop spring.
Identification of an oil pumping problem
If the operator knows how the booster pump works, he will be able to figure out how to remove the chainsaw pump. A minimum of locksmith skill and a minimum of tools are required to make this and then repair the assembly.
Keep in mind that identifying the problem of the oil pump will allow you to understand what disassembly of the component needs to be done, complete or partial. If you are afraid of not being able to cope with a complete disassembly, go to a service shop, where specialists use the technical potential for this. Of course, many of the parts that you can damage while disassembling the component can be replaced, but this replacement will cost you a pretty penny.
Please note that when the oil reservoir is full but the oil is not coming to the saw headset, the cause of the problem may not always be the oil pump. Sometimes in the process of disassembling the saw you can find faults in other elements, not related to the node. often than not replacing them solves the main problem.
In addition, before you blame all the troubles on the oil pump, check the oil filter, which when heavily contaminated not only impairs the operation of the oil pump, but can completely disable it. To check the oil filter, simply hold a paper over it, which will leave an oil streak. The density of the latter allows you to evaluate the condition of the filter and plan your next steps.
Important! Sometimes after repairing the lubrication system the consumable does not flow to the saw head, then you need to look for the cause of the failure in the mechanism in the regular adjustments. The problem can also result from a mismatch between the viscosity and the density of the oil. On the other hand, the appearance of this problem through carelessness or inattention can provoke the operator by installing the wrong guide on the power unit, for example, on an ordinary household guide from a professional powerful tool.
Operation of the oil plunger pump on the chainsaw.
The oil pump on chain saws is valve-less and mounted on the crankcase of the chain saw on the drive side of the saw chain. The role of the valve in these pumps is performed by a segmented notch at the end of the plunger. The plunger is driven from the clutch by the actuator through a pair from the worm hub. It turns out that the pump plunger rotates in the same direction and in doing so it itself closes the inlet and outlet passages of the oil pipeline in a cycle, combining the function of the valves.When the segmented notch at the end of the plunger opens the inlet passage of the oil supply line, the plunger extends slightly out of the pump working chamber, thereby gripping the oil from the line through the open port. As the plunger continues to rotate, the inlet port of the pump’s oil chamber closes and the discharge port opens. At the same time, the plunger slides in and pushes the trapped oil into the oil supply line to the lubrication point.
In one rotation around its axis, the plunger makes one reciprocating movement along its axis, the stroke of which is regulated by an eccentric screw installed transversely to the end of the plunger shaft. Some people like to call it a cam.
The eccentric assembly rests against a central projection on the plug stem end; the larger the angle of the adjusting screw, the farther the eccentric on it pushes the plug shaft away from itself. At the highest eccentric deflection the oil cannot be pressurized by the pump. No lubrication of the saw chain.
In addition to the central projection on the plug shaft, there is an annular projection with a profiled surface that determines the stroke of the plug along its axis. That is, the oil take-up and discharge rate.
There is a metal spring on the plug shaft which is supported on one side against the oil pump housing and constantly pushes the plug shaft against the adjusting screw.
The profiled surface of the annular protrusion is in contact with the cylindrical body of the adjusting screw. They have a mating point that, as the plunger shaft rotates, sets a value that limits the movement of the plunger along its axis and affects how the plunger grips and presses the oil.
The oil pump will operate at maximum efficiency if the cam of the adjusting screw makes no contact with the center projection on the plug shaft. As the adjusting screw rotates, the eccentric will move toward the protrusion and push the plunger shaft away from itself. The amount of oil the pump dispenses will then be based on the position of the eccentric against the cam on the plug shaft, and in this example, the amount of oil the pump dispenses is adjustable.
Chainsaw plunger oil pump malfunctions and troubleshooting.
It often happens that there is no oil flow to the saw chain, even with the adjustment screw in the maximum oil flow position. There are not many causes:
preventative measures
The chainsaw oil pump should be serviced periodically to prevent leakage. During and after operation, oil leaks must be monitored and if any are detected, retighten the connection elements immediately.
Check the lubricant level in the reservoir before starting work. It’s best to use manufacturer-recommended oil for the chain. Under no circumstances should waste material be poured due to its heterogeneous structure and presence of metallic inclusions.
To prevent vacuum clogging in the lubrication system, periodically blow through the oil pump passages with compressed air. After you have finished sawing, clean sawdust and dirt from the machine. At the beginning of the season it is necessary to suspend the chainsaw for a few minutes in an upright position in the operating position in order to allow the lubricant to spread evenly through the channels.
Working of the oil pump on the chainsaw.
The chain saw oil pump is valve-less and is installed on the side of the chain drive on the chainsaw. The valve function of these pumps is taken over by a segmented notch at the end of the plunger. The plunger is driven in rotation by the clutch coupling via a pair from the worm hub. It turns out that the pump plunger rotates in the same direction and closes the inlet and outlet passages of the oil line in the cycle itself, thus combining the function of the valves.When the segmented notch at the end of the plunger opens the inlet port of the oil supply line, the plunger extends slightly out of the pump working chamber, thereby capturing oil from the line through the open orifice. As the plunger continues to rotate, the inlet port of the pump oil chamber closes and the discharge port opens. At the same time, the plunger retracts and piston forces the trapped oil into the oil supply line to the lubrication point.
In one rotation about its axis the plunger makes a reciprocating movement along its axis, the stroke of which is adjusted by an eccentric screw installed crosswise at the front end of the plunger shaft. Some people like to call it a cam.
The eccentric end rests against the central cam on the plug shaft end; the greater the angle of the adjusting screw, the farther the eccentric on it will deflect the plug shaft away from itself. When the eccentric is at its most deflected, oil cannot be pumped by the pump. The saw chain is not lubricated.
In addition to the central projection on the plug shaft there is an annular projection with a profiled surface that defines the stroke of the plug along its axis. That is, the oil pickup and discharge rate.
There is a metal spring on the plug shaft that rests against the oil pump housing and constantly pushes the plug shaft against the adjusting screw.
The profile surface of the annular shoulder makes contact with the cylindrical body of the adjusting screw. A coupling is formed at the joint that limits the movement of the plug along its axis when the plunger shaft rotates and which affects how the plunger grips and presses oil.
The oil pump will operate at maximum efficiency provided the eccentric adjustment screw is not in contact with the center projection on the plug shaft end. As the adjusting screw rotates, the eccentric will move closer to the lug and push the plunger shaft away. In that case the amount of oil the oil pump will deliver will depend on the position of the eccentric in relation to the plug shaft, and in this example the amount of oil the pump will deliver is adjustable.
Malfunctions of the chainsaw plunger oil pump and troubleshooting.
It often happens that the saw chain is not supplied with oil even if the adjustment screw is set at maximum oil flow. There are not many causes: