The ends consist of a body in which a standard bearing is housed. They can be supplied with an external or internal thread, right or left handed, with welded extremities. They are standard products, the steel on steel versions needing lubrication; steel on bronze with PTFE, and steel on PTFE material not requiring maintenance. Choice of a type, as with the bearings, depends essentially on the use for which it is destined. As far as construction characteristics of the various types of ends are concerned, refer to the previous table. The most important series in the range is represented by ends for hydraulic applications are divided into two groups:
• Hydraulic rod ends internally threaded,
• Hydraulic rod ends with welded ends.
Considering the field of application, these ends are usually supplied in series, with steel on steel surfaces, where are situations of alternate loads. These are ends produced and constructed especially for these applications, as in the case of connecting rods and hydraulic cylinders where maximum security of anchorage is required.
The TAPR…CE series represents the best possible fixing factor, with infact equipped connector, having an internal thread, with a longitudinal cut so as to permit optimum fixing on the thread by way of two locking hexagon socket screws.

SELECTION GUIDE

Multiple conditions of use for bearings and ends determine their different construction characteristics and choice of materials.
There are numerous factors which influence the choice of bearing or end and all must be considered with great attention: LOAD, MAINTENANCE, WORKING TEMPERATURE, TILTING ANGLE.
To determine type, dimension and materials for working surfaces of a bearing or end, it is fundamentally important to understand the extent and direction of the load as well as the way in which it functions.

All the spherical plain bearings are able to support high radial load and, within certain limits, axle loads, in both directions which move simultaneously. 

Loads Which Move In One Direction

A situation in which the load always moves in one direction in the same way, and in this case, the area of the load is always on the same side as the bearing. For applications where the bearing is subject to static stress or many be subject to very small movements under load (but comparable to almost static stress). 
The use of plain bearings is recommended or ends with surfaces steel on steel. On the other hand when a bearing is subject to dynamic stress, spherical bearings or maintenance free ends are recommended.

Loads Moving In Alternate Directions

In this case it is recommended the use of spherical bearings or ends with surface steel on steel, use of spherical bearings or maintenance free bearings is foreseen only within certain limits.

Maintenance

Working temperature

Another important element having effect on the component materials of the bearing and ends.  As a rule, all the bearings can be used without problems in a temperature ranging from -30ºC to +50ºC. In higher temperatures reductions in load capacity are registered and it is advised specific analysis.

Tilt angle

Calculation of duration and sizing

To work correctly in the choice and sizing of the bearing, various factors must be taken into consideration and categories to consider are load, movement, duration, and lubrication.
Loads and impact, working environment and cleanliness are not in fact taken account of the analytical calculation. Knowledge of the intensity and direction of the loads is indispensable. For the calculation of the technical duration it is considered that load F coincides to the value of load of duration P, when the force moves un a purely radial direction and the size and direction do not vary during the operation (see diagram).

In the case of stress being, at the same time, axle and radial, a value of calculation P must be introduced in the calculation of duration that takes account of the influence of the combined moving forces (see diagram)

We calculate the value P with the formula:: P = Kf * FR, Where
P-dynamic load equivalent in К_н

FR- radial load in К_н

FA-axial load in К_н

Kf-correction coefficient that in this case is obtained by the formula Kf = 0,978 * 21,546 * FA / FR

Movement and Frequency

The presence of movement and its frequency characterize the dynamic condition of the operation (see diagram).

From the diagram it is possible to identify three types of movement expressed in the following categories
• Angle of oscillation ß;
• Angle of tilt a ;
• Angle of movement β1 in case of combined movements of oscillation and tilt. ß₁

         _____
b₁= |/b²+a²

Frequency

The number of movements is expressed in units of time and dimensionally is expressed in min-1.
It is introduced in the calculation function without periodical breaks.

Load coefficient

The coefficient of dynamic load C is used to calculate duration when we are in the presence of a dynamic type of stress that is when during loading there are oscillating tilt movements or rotating movements.
For use in this category it is indispensable for the load to move in a radial direction.
Dynamic applications represent the maximum permissible load and exploiting it completely does not allow a long duration. The relationship C/P is usually found in a range 1-5 inclusive and never less than 1.
The coefficient of static load C0 represents the maximum permissible static load on the bearings and ends before breakage or damage occurs to the grooved surfaces, used in cases of stress due to shock loads. For these definitions, a sufficiently rigid housing is assumed to exist so as to prevent deforming the bearing itself.

Pressure

An adequate specific load is necessary to obtain duration of exercise sufficient for our use. The specific pressure is a criterion of evaluation which is very important to the choice of bearing it is determinable knowing that.
 Р = К * Р / С,
К -value of specific load , Н/mm² (shown in the table.)
Р - load equivalent in кН
С - coefficient of dynamic load in кН available in the dimensional table

Using the calculation, based on laboratory tests, we can express the quantity of movements or the hours of operation that the greater part of a determinate number of bearings arrives at equal to the operating conditions, before damage or breakage.

Formulas for the calculation of duration with single lubrication

а). Determination of dynamic load equal to Р,
 P = FR * Kf  (see formula),

 
b). Determination of dynamic load equal р,
 p = 100 * P / C , Н/mm² ,

c). Determination of average dragging speed V,
V = 2.91 * 10 ^-4 *ds * ß* f , mm/s,

Where ds - is the diameter of the sphere (see dimension table)
ß - angle of oscillation in graduation, 
f - is the frequency of oscillation in turns

d). Calculation of duration L,

Where f1 load direction factor In one direction =1 , Alternate = 2
f2 load factor  for p = 1÷12.5 =42

                                                  per p = 12.5÷100= p^1.48 
Formula valid for temperatures ≤150ºC

e). Formula Lh

In case of it being necessary to establish the duration of bearings or ends with occasional lubrication or maintenance free we would ask you to contact our service department.

Calculation of life of the end

To calculate the duration it’s necessary to check the load given to the bearings, the calculation of the duration of each single bearing and the load equivalent to P on the bearing does not go above the load P given to the end.
We shall introduce reduction factors in the case of the load being pulsating or alternate.

Pa = Co / fr,
Where  Ра  - is the load given to the end in кН
         Со – Coefficient of static load end in Кн
         fr -  Coefficient of load that for constant load is equal to 1, while for a pulsating or alternating load it is 2.71.

Lubrication and maintenance

The lubricant, grease or oil, has the purpose of separating the dragging metallic surfaces, to protect against corrosion and to reduce friction. The exact choice of lubricant is made taking the type of stress the bearing will be subject to into consideration.
For a fairly vast field of application, it is recommended anti-corrosion lubricant, resistant to pressure, with a soap base with solid lubricant additives and EP.
It is a good rule to carry out an initial lubrication followed by various phases of relubrication and at the end to substitute the residue of the lubricant which has been used and allow the flushing out of impurities. We do not need to lubricate the maintenance free bearings because it would impede the transfer of PTFE particles from the internal ring to the counter surface of the external ring. So therefore no lubrication system is planned for the bearings or the ends.
For regulation DIN 648 ends, that is TFI…FK, TS…C, TFE…MK it is envisaged a greaser with a nominal diameter of 25 mm. for smaller diameters it is envisaged only one bore hole on the terminal so as to avoid diminishing resistance.
For regulation DIN 24338 ends, that is TAPR…CE are supplied with the same greaser M6 for all dimensions up to the size 110 mm; for bigger sizes M8 greaser. This is also the case for ends of the TS…N, TAPR…U, TAPR…N, and TS…CE-N series.

Operating temperatures

For ends with a steel/steel bearing the field of use is between -50ºC and +200ºC, even though at +180ºC it is found the load capacity diminishes. It is, however, the operational fields of the lubricants that determine this limit. Ends with a bearing of steel on PTFE the operating field is between -60ºC and +150ºC.
Another important limitation to both alternatives is due to the thermal resistance of the 2RS capacity which being constituted for the large part of poliurate materials, which permit an operational field of between -20ºC and +90ºC.

Bearing tolerances recommended

So as not to prejudice the proper functioning of the bearing it is recommended the following tolerances:

Radial Bearings        М7 / m6 ,  For Steel Housing
Steel / Steel    N7 / m6,  For Light Metal Housing.   

Radial Bearings        К7 / m6,  For Steel Housing
Steel / PTFE     PTFE ,  For Light Metal Housing