Torsional oscillation calculations from Scania
Scania's torsional oscillation calculations are made with direct frequency response for all configurations up to 350 Hz in a linear system for the engine speeds in question. The calculation is based on technical data provided to Scania by the customer or manufacturer for parts forming part of the elastic mass system which are not manufactured by Scania.
An approved calculation forms a guarantee against damage caused by torsional oscillations for all rotating parts from Scania that are included in the engine installation under Scania's general warranty commitments. The approval should not be regarded as a general system warranty in any other respect. Scania only takes responsibility for parts in Scania's product range and not for any other parts. Scania can, however, give a warning if the calculation shows that non Scania parts are subjected to high torsional amplitudes. scania trucks,trucks scania,scania trucking,scania cars,scania car,scania truck usa.
Torsional oscillation arises in any shaft system which includes a combustion engine. Depending on the combination of the design of the shaft system and the operating speed, these oscillations may attain high amplitudes and therefore place great strain on the equipment. This may even lead to total breakdown in a part of the shaft system. This process may be very rapid.
Connection of sensors for external monitoring systems
External monitoring systems for classed engines require in some cases that extra sensors are connected so that the following operating conditions can be monitored:
- coolant pressure
- coolant temperature
- oil pressure
- oil temperature
- fuel pressure
- engine speed
- charge air pressure (DI16 only)
- charge air temperature (DI16 only)
The following pages show suitable positions for installing such sensors. Scania offer a classified electrical system for monitoring of coolant pressure, coolant temperature, oil pressure, fuel pressure and engine speed. How to connect the Scania monitoring system is described in the installation manual 03:03 – Instrumentation 2.0.
Side-mounted power take-offs
The maximum torque that can be taken off from units connected to power take-offs is indicated on the following pages. The specified maximum torque assumes that the driven units have a relatively even drive torque, e.g. centrifugal pumps, gear pumps or vane pumps.
Connection of flexible coupling to front end of crankshaft
The engine must be equipped with a shaft journal or flange driver which is mounted on the crankshaft hub so that a flexible coupling can be connected at the front end of the crankshaft.
The transmissible torque and power in the case of direct connection to the front end of the crankshaft are limited primarily by engine type and the type of joint between the crankshaft and hub.
Crankshaft pulley with two or more belt grooves
The belt grooves are designed for 12.5 mm (0.5") narrow V-belts, but A section Vbelts can also be used. The transmission capacity of the V-belts determines the power available. Therefore it is important that the belt manufacturer's instructions are adhered to when calculating transmissible power.
In order to avoid impermissible radial forces at the front end of the crankshaft when there are many belts in the transmission, the driven units should be located so that the forces balance out each other.
Belt transmission in multi-engine installations
In multi-engine installations with a belt transmission, the alignment of the engine and bearings on the frame should be checked after the installation is complete. In addition, you should also check that the pulley is properly secured to the shaft so that it cannot wander after start-up.
Shafts A and B should be sufficiently parallel that their centrelines fall within a circle with a diameter of 0.8 mm. See the illustration. Check that the support bearings have sufficient lubricant as per the manufacturer's instructions. There are both oil and grease lubricated bearings.
Scania Belt transmissions
Belt transmissions are appropriate especially in multi-engine installations where two or more engines drive a common output shaft. One of the advantages of a belt transmission is that it is easy to adapt to the appropriate gear ratio.
The belt transmission functions to some extent as a flexible coupling, runs silently and has a long service life. Apart from checking belt tension and alignment, belt transmissions do not require any special maintenance. There are belt transmissions with different types of belts, such as single V-belts and devices consisting of two or more V-belts coupled together.
Which belt type to choose depends on several factors. More information and help in dimensioning a belt transmission can be obtained from the belt manufacturer. Large lateral forces may arise during belt operation. Accurate alignment and checking of the belt tension are therefore necessary. A different belt tension results in increased bearing load and displacement of the centre of the load. The lateral loading can be reduced by e.g. changing the size of the pulley. The manufacturer can provide information about permissible lateral forces and belt tensioning for belt transmission in each case.