Housing Seals

What are housing seals?

Housing seals are seals that fit into the seal grooves at each side of a split plummer block housing, where the shaft passes through. They keep grease in the housing and stop dirt, dust, and water reaching the bearing. Housing seals come in a range of designs, from simple felt seals to heavy-duty labyrinth and taconite seals, so the level of protection can be matched to the conditions.

A standard housing seal arrangement is made up of:

• A seal that fits into a groove in the housing on each side of the bearing
• A sealing element, such as rubber lips, felt, a V-ring, or a labyrinth, that seals against the shaft
• A size that matches both the housing groove and the shaft diameter
• Often a split design, so the seal can be fitted without removing the shaft.

Housing seals are chosen to suit the conditions.

• Contact seals, such as lip seals and V-rings, rub lightly on the shaft and give a tight seal in dusty and damp conditions.
• Non-contact seals, such as labyrinth seals, leave a tiny gap so they create no friction, which suits higher speeds.

Most housing seals are designed for a specific housing series and size, such as SKF SNL split plummer block housings.

Why are housing seals essential?

Contamination is one of the main causes of early bearing failure. A plummer block may be working on a conveyor, crusher, or fan in a dusty, wet, or dirty environment, and without good seals, grit and water soon find their way into the grease and damage the bearing. The right housing seal keeps the grease clean and the bearing protected, which extends service life and reduces downtime.

Because seals are a separate part, they can be upgraded to suit tougher conditions, such as fitting a taconite seal in a quarry, or replaced on their own when they wear, without changing the housing.

Typical applications include:

• Conveyors and belt drives
• Fans and blowers
• Crushers and screens
• Quarrying and mining equipment
• Pumps and compressors
• Paper and pulp machinery
• Agricultural and food processing machinery
• General industrial machinery using plummer blocks

The main types of housing seals

• Double-lip seals (TSN..G) - Split rubber seals with two lips that seal against the shaft. They are easy to fit and give good protection in general and moderately dusty conditions.
• Four-lip seals (TSN..L) - Split seals with four sealing lips, for better protection against dirt and moisture than a double-lip seal.
• V-ring seals (TSN..A) - A rubber V-ring that turns with the shaft and seals against a face, combined with a steel element. They give good protection against dust and water splash.
• Felt seals (TSN..C) - Felt strips with a supporting ring, which seal lightly against the shaft. They suit grease-lubricated bearings in relatively clean, dry conditions.
• Labyrinth seals (TSN..S) - Non-contact seals with a winding path that blocks contamination without touching the shaft. They create no friction, so suit higher speeds.
• Taconite seals (TSN..ND) - Heavy-duty seals with a radial labyrinth and grease-filled chambers, designed for very dirty environments such as quarries and mines.

How to choose the right housing seals?

• Housing and shaft size - Choose a seal that matches the housing series and size, and the shaft diameter. A seal for the wrong housing or shaft will not fit or seal properly.
• Level of contamination - Use felt or double-lip seals for cleaner conditions, four-lip or V-ring seals for dusty or wet conditions, and taconite seals for very heavy contamination.
• Speed - Contact seals create a little friction and heat, so for higher shaft speeds, a non-contact labyrinth seal may be better.
• Temperature and lubricant - Check the seal material suits the operating temperature and the grease being used.
• Shaft condition - Contact seals need a smooth, clean shaft surface where they run. Check the shaft for wear before fitting new seals.

Essential references and specialised ranges

How the numbering works:

Housing seals are usually referenced by series, size, and seal type. In the widely used SKF TSN system:

TSN = housing seal for split plummer block housings

The number = the housing size the seal fits, which also sets the shaft size

The letter at the end = the seal type

Examples:

TSN 510 A = V-ring seal, 45mm shaft

TSN 516 C = felt seal, 70mm shaft

TSN 520 A = V-ring seal, 100mm shaft

TSN 213 G = double-lip seal for a 213 size housing

Always check the housing reference and shaft diameter before ordering.

Suffixes:

G = double-lip seal

L = four-lip seal

A = V-ring seal

C = felt seal

S = labyrinth seal

ND = heavy-duty taconite seal

Suffix codes vary between manufacturers, so check the supplier’s catalogue for the exact meaning.

FAQ - All you need to know about housing seals

Which type of housing seal do I need?

It depends on the conditions. Double-lip and felt seals suit general, cleaner conditions. Four-lip and V-ring seals suit dusty or wet conditions. Taconite seals suit very dirty environments, and labyrinth seals suit higher speeds.

Do I need a seal on both sides of the housing?

Where the shaft passes through both sides, yes, a seal is needed on each side. At the end of a shaft, one side can be closed off with an end cover instead.

Can I replace housing seals without removing the shaft?

Many housing seals, such as double-lip and four-lip seals, are split, so they can be fitted around the shaft without removing it. Check the seal design before ordering if this is important.

Do housing seals need lubrication?

Contact seals should be lightly greased when fitted, to reduce friction and wear on the first run. Taconite and labyrinth seals have grease-filled chambers that are packed with grease to help keep contamination out.

How do I fit housing seals?

Clean the seal grooves in the housing and check the shaft is smooth where the seal will run. Lightly grease the seal, then fit it into the groove in the housing base, with any split positioned as the manufacturer recommends. Fit the bearing and shaft, then fit the housing cap so the seal is held in both halves of the groove.

How do I identify the housing seal I need?

Check the reference on the old seal or the housing, such as an SNL housing size, and measure the shaft diameter. The seal must match both the housing groove and the shaft.

How can I tell if a housing seal needs replacing?

Warning signs include:

• Grease escaping from the housing around the shaft
• Dirt, dust, or water in the grease
• Worn, torn, or hardened lips or felt
• A groove worn into the shaft where the seal runs
• The bearing running rough or noisy because of contamination