When to change auxiliary drive belts and what affects their wear?
V-ribbed belts are widely used to transmit torque in a number of different components: an air conditioning compressor, a generator or a power steering pump. Due to the reduction in the working volume of engines and the improvement of their environmental performance, the belts of additional equipment work today in much more difficult conditions than several years ago. What is the frequency of replacement of these belts and what determines their wear?
V-ribbed belts are mainly used in the drive of auxiliary units of internal combustion engines. In hybrid cars there are no such belts, here the air conditioning compressor or generator is driven by independent electric motors. Given that currently the number of cars with internal combustion engines in use exceeds the number of hybrid ones, manufacturers are striving to simplify the maintenance of these systems (which, unfortunately, is not equivalent to increasing the service life). Therefore, many new cars are equipped with the so-called “serpentine system”, when one V-ribbed belt simultaneously drives several components. Belts work on guide rollers, overrunning clutches of generators, as well as dampers of torsional vibrations of the crankshaft. An important element is the tensioner, which maintains a constantly specified tension. In this case, it is very important to install the belt of the correct length. One of the most common mistakes made by service stations is the low tension resulting from installing too long a belt.
“Each belt is subject to periodic replacement, and its malfunction in the first place can be judged by the characteristic whistle. The frequency of replacement is always determined by the vehicle manufacturer. As a rule, it is approximately 100,000 km, but it directly depends on the operating conditions: for cars operating in difficult conditions (for example, a tow truck, taxi or cars with trailers), this value is significantly lower. In older cars, it was possible to tighten the auxiliary drive belt by hand. Today, when automatic tensioners are responsible for this, if there is any sign of wear of the V-ribbed belt, replace it with a new one, ”advises Tomasz Ohman from SKF.
During operation, the belts are subject to wear: the rubber elements are erased, and the rubber itself may harden and crumble. An additional hazard is any chemicals, such as cleaners or used engine oil, which can reduce the durability of rubber on contact. Adverse effects are also exerted by weather conditions. Accessory drive belts usually do not have a protective coating, so frost or, for example, dirt can accelerate the destruction of the material from which they are made. Incorrectly installed or worn pulleys also affect belt wear..
“However, the whistle of the auxiliary drive belt does not always mean wear of only this component. This may indicate a malfunction of any of the devices that set it in motion. The belt starts to slip on the roller due to overload. The increased resistance that the belt has to overcome is usually due to a faulty generator (for example, its bearing), low battery charge, or because of an electrical system. Given this, it is necessary to conduct a visual inspection of all elements and devices, as well as carefully check the health of their work. SKF service bulletins pay special attention to this, ”emphasizes Tomasz Ohman.
Untimely replacement of the auxiliary drive belt may cause it to break during movement. In this case, the extent of damage will depend on the design of the engine. If the broken V-ribbed belt was responsible for driving the coolant pump, continuing the trip can lead to irreversible consequences. In the absence of proper cooling, the engine will quickly overheat and this will lead to costly repairs. In the event of a breakage of the (separate) drive belt of the generator, the battery charge will last for several kilometers.
“In many compact engines, a single V-ribbed belt can drive multiple devices. Because of this, smaller pulleys are used that are mounted close together. As a result, the angles of the bend of the belt increase, which significantly complicates the conditions of its operation. This means that in addition to regular inspections and timely replacement, the use of high-quality parts makes a significant contribution to the proper operation of the belt. For example, SKF V-ribbed belts, which are being created in close collaboration with vehicle manufacturers. The new V-ribbed belt is relatively inexpensive. Therefore, we recommend changing the belt when replacing the timing drive, in which case this component must still be dismantled, ”concludes Tomasz Ohman.
SKF is a leading global manufacturer and supplier of bearings and bearing assemblies, lubrication systems, mechatronics, seals, condition monitoring equipment and related products, as well as providing services, engineering consulting and technical training. SKF has representative offices in more than 130 countries, and there are approximately 17,000 SKF distributor companies in the world. In 2018, SKF’s annual sales reached 85 713 million Swiss francs. crowns, and the number of full-time employees was 44,428 people. www.skf.ru
® SKF – registered trademark of SKF Group.
Automotive bearings: where are they located and how to recognize their malfunction? Bearings are components that are widely used in automobiles, without…
How to replace pads The critical wear of the front pads, as a rule, is evidenced by an unpleasant metallic rattle in the area of the front wheels at…
How to drive a car abroad? A series of tips: life stories and recommendations – mine and more experienced car travelers How it all began? I started…
How to drive a car in the rain For an inexperienced driver who has recently received a driver’s license, driving in bad weather conditions such as heavy…