Glossary of technical terms

Axial force acts in the direction of the axis of rotation of the bearing. Axial bearings designed predominantly for axial load have a contact angle α > 45°.

Radial force acts perpendicular to the axis of rotation of the bearing. Radial bearings designed predominantly for transmitting radial load have a nominal contact angle α ≤ 45º.

Combined load consists of simultaneously acting radial and axial loads. The axial load capacity of the bearing depends on the contact angle. The larger the angle, the greater the axial load capacity of the bearing.  Bearings for transmitting combined load are called combined bearings.

Bearing clearance is the value of the displacement of one ring of an assembled bearing relative to the other ring from one extreme position to the other. The displacement can be in the radial direction (radial clearance) or in the axial direction (axial clearance).

A bearing cage is the component that typically guides the rolling elements. The cage holds the elements at a uniform distance from each other and prevents them from touching one another. Materials such as steel and plastic are most commonly used for bearing cages.

Solid hub (monobloc) with pre-bored hole or without hole

For V-belt pulleys, the standard design is a pulley without a pre-bored hole, i.e., with a solid hub. For timing pulleys, the pulley is supplied with a basic pilot bore. Flat pulleys are not supplied in this design, only for Taper Bush.

For Taper Lock bushings

The pulley is mounted on the shaft using a bushing. This tapered bushing with an outer cone, on which the pulley is fitted, is tightened with two screws and secures the pulley in the correct axial position. You can then choose from several diameters for the inner bore of the bushing, which is already made including a keyway.

On System P locking bushing

The System P tapered bushing, like the Taper Lock bushing, already has a finished bore with a keyway, so assembly on the shaft is carried out by simply screwing it together with the pulley.
 

Solid hub without pre-boring

For Taper Lock bushing

V-belt pulleys

V-belt pulleys are designed for all types of V-belts and multi-ribbed belts. Design according to ISO 4183 (DIN 2211) for narrow, classical and raw edge V-belts.

Multi-ribbed (Poly-V) pulleys

Multi-ribbed pulleys (ribbed pulleys or poly-v pulleys) in profiles PJ, PK, PL and PM are the basic type of ribbed pulleys. Their design is based on the ISO 9982 (DIN 7867) standard.

Flat pulleys

Flat belt pulleys are designed for power and speed transmission via a flat belt. The design of flat pulleys is based on the DIN 111 standard. The most common design is flat pulleys with a crowned contact surface.

Timing pulleys

Timing pulleys are manufactured for all types of timing belts in HTD, STD, CTD, GTR, H.O.T., T and AT profiles, as well as trapezoidal inch profiles. Their design is based on the ISO 5294 (DIN 7721) standard.

Timing bars for pulley production

Timing bars (timing bar stock) serve as a semi-finished product for the production of timing pulleys. They are manufactured in various profiles corresponding to belt profiles.

For variable speed belts

Variable speed pulleys are pulleys with spring-loaded flanges and the possibility of a continuously variable pitch diameter Dp. In our e-shop, we offer these pulleys from manufacturers POGGI or SIT.

The diameter theoretically describes the position of the pitch circle, which is always larger than the outer diameter of the pulley. The pitch diameter can easily be calculated from the ratio – P × Z = π × Dp.

Other symbols used: P – Pitch, De – Outer diameter of the pulley

• h – Total belt height
• b – Belt width, the longer base of the trapezoidal belt profile.
• α  – V-belt angle - the angle enclosed by the working surfaces measured on a straight section of the belt in a tensioned state
• Li – Inside length of the belt measured on the inner base of the belt in a tensioned state.
• La – Outside length of the belt measured on the outer base of the belt in a tensioned state.
• Lw=Lp=Ld – Pitch (datum) length of the tensioned belt in the neutral fibers. Neutral fibers are fibers of the belt cross-section that maintain the same length during deformation of the cross-section when the belt transitions from linear to circular motion under constant belt tension.
• Le – Effective belt length
• bw – Pitch (datum) width of the belt, the belt width at the neutral fibers of the belt.

In practice, we mostly encounter offers from companies trying to push their solution into the machine design. Suppliers try to find applications where their offered product could be used. However, each component has its maximum technical limits, and in some cases, its use is not realistic.

When it is not suitable to use a belt

• The transmitted power is very high and the speed is very low, e.g. at 100 kW and 50 rpm, the torque is about 19,100 Nm. This is unrealistic for a belt drive, and another solution must be sought.
• The pulley diameters are too small for the selected belt type, e.g. a pulley diameter of 100 mm for C/22 or SPC belts. This diameter is too small for these belts, and the belts would be damaged during bending. Larger pulleys, a different type of belt, or another solution must be used.
• The ambient temperature is too high, e.g. more than 150 °C. This is an extreme temperature for the belt material, and belts are unable to withstand these temperatures long-term. In such a case, a chain or similar must be used.
• The speed and pulley diameter are high, e.g. a pulley diameter of 350 mm and a speed of 3000 rpm. This would result in a peripheral speed of 55 m/s. This speed is too high for a V-belt or a timing belt. A flat or multi-ribbed belt must be used, or the entire drive design must be changed.

Comparison of belt usage according to maximum peripheral speed

• Wrapped V-belts are suitable for speeds only up to 35 m/s.
• Raw edge cogged V-belts XPZ, XPA, XPB, XPC and ZX, AX, BX, CX can operate at speeds up to 50 m/s. There are applications where these V-belts operate at speeds above 50 m/s, e.g. up to 60 m/s in blowers. However, accurate calculations and tests are required, and special VTP spheroidal graphite iron pulleys with sufficient balancing must be used for the drive.
• Multi-ribbed (Poly-V) belts can operate at maximum speeds up to 60 m/s. These belts are successfully used to replace V-belts in high-speed drives.
• Timing belts are applicable for maximum speeds of 40 to 50 m/s, depending on the profile size. Special types for high-speed drives can operate up to 60 m/s. For timing belts at high speeds, it is necessary to monitor drive noise. Belts with STD or CTD profiles are designed for the highest speeds.
• For special CXA timing belts, which are designed for low-speed drives, the construction and material of the belts limit the maximum peripheral speed to 25 m/s. These belts are designed for other types of drives than the transmission of the highest speeds.
• Flat belts can be used for maximum speeds of 80 to 100 m/s depending on the type. However, the disadvantage is lower transmitted power, wider width, and the need for higher tensioning forces.

V-belt marking according to standard

• For classical V-belts, a letter is given, i.e. the profile, and a number representing the inside length in inches. This is followed by a number in millimeters Li (inside length).
• For narrow V-belts, the profile and the length in millimeters Lw (pitch/datum length) are given.
• For automotive V-belts, the profile and the length La (outside length) are given.

How can individual types of V-belts be replaced?

The most accurate replacement of individual belts is by converting to the pitch length Lw or Ld. We convert the individual belts, which are marked with a different length, to the pitch length and use this to find a suitable replacement in a different profile or belt type.

• Accurate drive sizing, selection of the correct safety factor
• Do not unnecessarily increase the number of belts or belt width
• Use of modern profiles for high power transmission
• Setting the correct belt tension and checking it
• Operation within the rated load range

Roller chains are the most commonly used chains, applied in all areas of drives. A roller chain belongs to the category of articulated chains. There are precisely defined clearances between the individual moving parts, which ensure the correct operation and flexibility of the chain. The chain consists of inner and outer links. The inner chain link consists of two inner link plates and two hollow bushes pressed into the plates. The outer link again consists of two plates into which two pins of a smaller diameter than the inner diameter of the bushes are pressed.

Roller chains are the most widely used chains in all areas of transmission, especially for drives with high load and high speeds. All types of chain can be ordered with a surface treatment (galvanized plating or stainless steel design) of all components or only certain parts.

Single-strand roller chains - according to DIN 8187 (European)

Double-strand roller chains - according to DIN 8187 (European)

Triple-strand roller chains - according to DIN 8187 (European)

Conveyor chains are designed for all types of conveyors, transport and assembly belts. Any type of attachments can be mounted on these chains.

Conveyor chains - according to DIN 8165

Conveyor chains - according to DIN 8167, ISO 1977, CSN 26 0401

Galle chains are used to transmit high tensile force at low peripheral speed - max. up to 0.3 m/s. These chains can be made of stainless steel for use in water.

Galle chains without washers

Galle chains with washers

They are used to transmit high tensile force at low peripheral speed - max. up to 0.3 m/s. These chains can be made of stainless steel for use in water.

Slow-speed bush chains - according to DIN 8164

Leaf chains are mostly used as tension or lifting chains. Examples: load chains in cranes and lifting equipment, as well as for holding counterweights and transmitting reciprocating forces.

Leaf chains LL - according to DIN 8152

The NLGI scale, which is standardized in ISO 6743/9 or STN ISO 65 6901, is used to designate the consistency (fluidity) of a lubricant.

Oil seals (Simmerrings, rotary shaft seals) are used to seal the spaces around rotating shafts. The oil seal is located in the installation space and is equipped with a sealing lip with a spring. The spring wraps around the lip and ensures the correct radial pressure. This seal makes it possible to separate two liquid or gaseous media with a low pressure gradient from each other on rotating shafts.

Overview of types

• Standard oil seals without dust lip type A (G)

• Standard oil seals with dust lip type AS (GP)

• Pressure oil seals type SY

• Oil seals with metal case type B

• Oil seals with metal case and reinforcing cap type C

• Oil seals without spring type "O"

• Oil seals with hydrodynamic lip ribbing

The most commonly used silentblocks are standard types 1-5. Silentblocks are designed for flexible mounting, shock absorption, active and passive vibration isolation, noise insulation, force transmission, protective mounting and the like. The high level of technology and a wide range of rubbers used enable the production of high-quality anti-vibration parts with the desired properties. Silentblocks are manufactured from rubbers based on NR, SBR and NBR in standard hardness of 55 ShA. The field of application of silentblocks is almost unlimited.

Silentblocks find application in all areas of industry such as automotive, mechanical engineering, transport equipment, agriculture, construction and medical technology.