Description
Cone Rubber Bellows for Variable-Diameter Components
Barbieri Rubber cone rubber bellows are flexible protections with a cross-section that varies between two different end diameters. The truncated-cone shape protects moving parts where the fixed side and the moving side have different diameters, or fits into asymmetric seats. They are standard catalog rubber components, but are also frequently produced as custom rubber bellows for specific applications.
| Code | Ø d1 (mm) | L1 (mm) | Ø d2 (mm) | L2 (mm) | L (mm) | Ø d3 (mm) | Ø d4 (mm) |
| SOF CON 2.5X25 | 2,5 | 2 | 22 | 2 | 25 | 25 | 33 |
| SOF CON 4.5X28 | 4,5 | 2 | 19 | 4 | 28 | 12 | 25 |
| SOF CON 06X32 | 6 | 1 | 18 | 4 | 32 | 18 | 24 |
| SOF CON 6.5X34 | 6,5 | 2,5 | 27,5 | 2,4 | 34 | 32 | 38 |
| SOF CON 6.5X32 | 6,5 | 2 | 28 | 5 | 32 | 20 | 34 |
| SOF 028 | 8 | 10 | 47 | 12 | 162 | 32 | 61 |
| SOF CON 8X50 | 8 | 4 | 27 | 10 | 50 | 27 | 32 |
| SOF CON 8.5X45 | 8,5 | 2 | 36 | 5 | 45 | 25 | 43 |
| SOF CON 09×50 | 9 | 5 | 60 | 10 | 50 | 20 | 30 |
| SOF 30X43 | 9,5 | 11 | 30 | 17 | 43 | 28 | 35 |
| CUF VAL P | 11 | 12 | 65 | 0 | 55 | 43 | 82 |
| GAL SOF 27610 | 12 | 7 | 22 | 7 | 24 | 31 | 36 |
| SOF CON 12X42.5 | 12 | 3 | 36 | 8 | 42,5 | 25 | 46 |
| SOF CON 12X130 | 12 | 10 | 70 | 16 | 130 | 40 | 75 |
| CUF VAL G | 14 | 14 | 84 | 15 | 78 | 61 | 102 |
| SOF CON 14X60 | 14 | 12 | 48 | 5 | 60 | 35 | 66 |
| SOF CON 14X29 | 14 | 10 | 25 | 9,5 | 29 | 25 | 30 |
| SOF CON 14.3X75 | 14,3 | 0 | 90 | 0 | 75 | 34 | 88 |
| SOF CON 15X84 | 15 | 12 | 62 | 4 | 84 | 40 | 76 |
| SOF CON 16X105 | 16 | 11 | 40 | 16 | 105 | 24 | 50 |
| SOF CON 18X44 | 18 | 4 | 44 | 2 | 44 | 48 | 48 |
| SOF CON 18X90 | 18 | 8 | 70 | 10 | 90 | 40 | 100 |
| SOF CON 20X33.5 | 20 | 2 | 37 | 3 | 33,5 | 38 | 42 |
| SOF CON 20X33.5X42.5 | 20 | 3 | 42,5 | 6 | 33,5 | 30 | 53 |
| SOF CON 20X165 | 20 | 20 | 87 | 18 | 165 | 65 | 135 |
| SOF CON 23X35 | 23 | 3 | 50 | 2 | 35 | 25 | 62 |
| SOF CON 23X170 | 23 | 15 | 90 | 12 | 180 | 62 | 116 |
| SOF CON 23.5X43 | 23,5 | 6 | 58 | 7,5 | 43 | 63 | 74 |
| SOF CON 27X208 | 27 | 15 | 56 | 5 | 208 | 63 | 80 |
| SOF CON 28X46 | 28 | 4 | 70 | 12 | 46 | 32 | 74 |
| SOF CON 28X50 | 28 | 5 | 50 | 8 | 50 | 50 | 65 |
| SOF CON 29X140 | 29 | 20 | 73 | 1 | 140 | 70 | 93 |
| SOF CON 32X35 | 32 | 12 | 54 | 1 | 35 | 60 | 95 |
| SOF CON 35.5X54 | 35,5 | 5 | 58 | 5 | 54 | 62,5 | 85,5 |
| SOF CON 45X55 | 45 | 6 | 108 | 7,5 | 55 | 80 | 100 |
| SOF 140X35 T | 40 | 30 | 110 | 10 | 130 | 41 | 104 |
| SOF CON 53X47 | 53 | 10 | 67 | 5 | 47 | 65 | 80 |
| SOF CON 60X170 | 60 | 10 | 130 | 10 | 170 | 80 | 130 |
| SOF CON 60X170 | 60 | 10 | 130 | 10 | 170 | 80 | 130 |
What a cone rubber bellows is for
The cone bellows is the right solution when the component to be protected does not have a constant section: for example when one end is fixed to a cylinder body or actuator with a given diameter, and the other end is fixed to a smaller-diameter rod or shaft. Without a cone bellows, intermediate cylindrical adapters would be needed, increasing cost, envelope and potential weak points. The cone rubber bellows protects from dust, splashes, oil and atmospheric agents while keeping flexibility and controlled elastic recovery.
Available compounds and typical hardness
Compounds used for cone bellows are the same as the bellows family: NBR, EPDM, VMQ silicone, FKM (Viton®), HNBR and NR/SBR, with typical hardness between 40 and 70 Shore A. Compound choice depends on the environment: mineral oils, fuels, water, steam, ozone, high temperatures, chemicals. EPDM is preferred for outdoor or UV-exposed parts; NBR for oils and fuels; VMQ silicone for extended temperature range or food/medical applications.
| Compound | Temperature range | Chemical resistance | Typical applications |
| NBR (Nitrile) | -40 / +130 °C | Mineral oils, fuels | Hydraulics, automotive |
| EPDM | -40 / +100 °C | Water, steam, ozone, UV | Hydraulics, outdoor, photovoltaic |
| VMQ (Silicone) | -60 / +200 °C | High temperature, biocompatible | Food, medical, high-T |
| FKM (Viton®) | -10 / +180 °C | Aggressive oils, solvents, fuels | Chemical, automotive, hydraulics |
| HNBR | -20 / +160 °C | Oil + high temperature | Heavy-duty hydraulics |
| NR / SBR | -50 / +90 °C | Good mechanical elasticity | Anti-vibration, general |
Standard catalog cone bellows and custom designs
Several diameter pairs are part of the Barbieri Rubber standard catalog, with active tooling and no cost for the customer. When the requested diameter pair, working length or flange geometry falls outside the standard, we produce custom cone rubber bellows: the customer provides at least a preliminary drawing with both end diameters, length, number of convolutions and desired compound. The dedicated mold is manufactured in cooperation with our trusted toolmaking partners.
Industrial applications
Cone bellows are used in hydraulics for cylinders with very different rod and body diameters, for piston protection and flanged connections, in pneumatics for non-cylindrical actuators, in automotive for steering components and linkages, on agricultural and earth-moving machinery for piston and rod protection, and in special applications where asymmetric geometry calls for a conical protection.
Frequently asked questions
When should I choose a cone bellows instead of a cylindrical one?
Choose a cone bellows when the two attachment points have different diameters. The cone shape directly covers the section difference, with no need for intermediate cylindrical adapters, simplifying assembly and reducing envelope size.
Are cone bellows available from stock?
Yes, some standard diameter pairs are catalog rubber components with no tooling cost for the customer. For non-standard diameter pairs or lengths, the custom design version applies.
Can I request a cone bellows with two specific diameters?
Yes, this is the typical custom-design request. Feasibility requires at least a preliminary drawing showing both end diameters, working length and indication of the application. The dedicated mold is manufactured in cooperation with our trusted toolmaking partners.
Which compound should I choose for a cone bellows?
For oils and fuels NBR; for water, steam, ozone and outdoor use EPDM; for extended temperature range or food/medical environments VMQ silicone; for aggressive oils and high temperatures FKM (Viton®). Selection is made case by case based on service conditions.
Which industrial sectors use cone bellows?
Hydraulics, pneumatics, automotive, vehicle service equipment, agricultural and earth-moving machinery, and special applications with asymmetric geometries. They are part of Barbieri Rubber’s technical rubber components for the global B2B market.
