Guide To Seals
Careful selection always pays in the end! Rotary Shaft Seals are engineered to give optimum performance and a long service life.
Both TTO and NTK rotary shaft seals are precision manufactured and subject to stringent quality control through all stages of production.
We offer full product traceability and all parts are manufactured in accordance to the industry recognised DIN 3760 standard.
DESIGN
Operating conditions together with performance requirements obviously affect the choice of rotary shaft seal. A wide range of special types and styles are available from stock and bespoke solutions can be designed to meet your individual needs and requirements.
The following standard designs satisfy the majority of applications…
Open Backed Seal (includes SC/R21, TC/R23, DC/R22, VC/R26 and KC style)
The rotary shaft seal(pictured) is constructed with a metal casing which is coved in a rubber material and can be used on any size of shaft.
The rubber covering prevents the mental casing from rusting and helps prevent damage to the housing during assembly.
This “standard” rotary shaft seal comes either in single or double lipped style. The single lip seal (SC/R21 or VC/R26) seals against internal media whereas the double lipped seal (TC/R23 or KC) seals against the internal media and offers an auxiliary lip which provides protection against dirt and dust.
The DC/R22 style rotary shaft seal is a double lipped and double sprung seal. This style offers a seal against two medias. It’s as simple as that!
The VC/R26 and KC style rotary shaft seal have the same lip features as the SC/R21 and TC/R23 styles but do not contain a garter spring.
This design is often used where space is at a premium or when a low friction application is required.
Open Backed Seal (includes SB/R4, TB/R6 and VB/R12)
Metal cased rotary shaft seals are identical in lip feature to their sister style rubber covered seal except they are not rubber covered!
A metal cased solution will be chosen when a more hardwearing seal is required.
The rick of damaging such a seal is minimised but fairly large force is required when fitting.
Such styles are mainly used on shafts with a diameter of less than 150mm.
Fully Enclosed Seal (includes SA/R1 and TA/R1)
As the name indicates, this style of rotary shaft seal is fully enclosed! The main benefit of this style is the very stable construction which in turn offers a better protected sealing member in comparison to the open backed style.
This style of seal is the hardest wearing as it seals with a reinforced metal case.
Such a style is mainly used on larger shafts when the diameter is beyond 150mm, or when a small shaft requires extra strength.
It is not unusual to see such a style used when a special rubber compound is required.
Fully enclosed seals are more commonly single lip but can be supplied with a double lip.
Motorcycle Fork Seal (TC4)
Two key features to the design of the motorcycle fork seal are durability and ride.
The requirements of this shaft seal is often extremely demanding, especially in off-road or motocross application.
TTO offer a high quality fork seal which provides both excellent ride and durability.
The solution these seal provide allow for both off-road and highway use.
The standard TC4 style shaft seal is designed with three lips and one spring. The DC4 type contains three lips and two springs.
The lip configuration allows these seals to operate under higher pressure than a standard rotary shaft seal.
It is common for fork seals to come fitted with stainless steel springs to provide extra protection to the elements and thus reduce the impact of rust and corrosion.
Gamma Seals (RB and 9RB)
Gamma Seals come in two styles, RB and 9RB. The gamma seal consists of two parts; sealing member and case. The gamma seal is designed to be fixed to the surface at a predetermined distance from the sealing surface, which is positioned perpendicularly to the shaft (eg the end wall of a bearing housing). During rotation the sealing lip rubs against the counter face under a contact pressure which is calculated to achieve a sealing function.
The seal also operates as a deflector ring with its centralfugal action contributing to excellent sealing function.
The gamma seal is primarily intended to for sealing against foreign matter such as liquid splatter and grease. However, it can also operate as a liquid seal under certain conditions. Typical applications include: Ball and Roller Bearing Housings, Electric Motors, Power Saws and Wheel Hubs. In Combination with a rotary shaft seal the gamma seal can either operate as a dirt seal or as a shield against oil flow.
Gamma Seals are available in two styles. The RB style comes with a metal ring which protects the rubber from damaged. In the 9RB style the metal ring is extended in the axial direction on the outer sheath.
V Rings (includes VA and VS)
V Rings are an axial seal with a rubber sealing element. The design is such that the rubber stretch fits onto a shaft and rotate with the shaft against a counter face. They are designed to offer protection from contamination to a primary seal. The design of the seal utilises centrifugal force to prevent contamination into the bearing chamber.
V Rings are available in a number of styles. The two most common are the VA and VS type. The VA type is the standard V Ring and comes with a straight back.
Common applications for the VA include conveyor rollers and appliances. The VS type has a wide body with angled back and is used in higher speed application such as automotive and agricultural.
End Caps (EC/VK)
End caps offer a simple solution to block unused ports in oil sealing applications and come in a wide variety of bore sizes.
FITTING
Correct fitting is of vital importance to the performance and life of a seal. A badly fitted seal can, moreover, cause damage to bearings and rotating parts, leading to costly downtime. Seal replacement should take place in as clean and dust-free surroundings as possible.
The shaft should be thoroughly clean. Remove all burrs, sharp edges, uneveness and particles, and apply a thin coating of pure mineral oil. Keep the seal in its wrapping until just before use. Carefully smear the sealing lip with pure mineral oil. Take care to fit the seal at right angles to the shaft, while ensuring that the lip is not damaged. Remember the lip diameter is somewhat less than that of the shaft.
If the shaft has a square shoulder, a special sleeve should be used when fitting the seal. The diameter of the sleeve must be somewhat larger than the shaft’s so that the seal can be eased over the edge without damaging the lip.
Use a bell tool or similar to distribute the load when pressing the seal into position.
If the seal is to be fitted with the open side outwards, a special tool may be required. Be careful with the sealing lip. It is sometimes necessary to remove the spring in order to position the seal properly.
LEAKAGE
Any appreciable leakage is very seldom the fault of the seal itself. It is most often the result of defects on the shaft or in the seal housing. It can also be due to the seal being of the wrong type or careless fitting. Try to trace the leak. If the leakage appears to come from the seal itself, carefully remove it and wipe it clean, and examine it.
