Pressed Housings

What is a pressed housing?

A pressed housing is a bearing housing made from pressed sheet steel instead of cast iron. It is usually made in two halves, which are bolted together around a self-aligning insert bearing to hold it securely. Pressed housings are light, simple, and low in cost, and are designed for light-to-medium duty machinery. They are commonly fixed to sheet metal frames or timber.

A standard pressed housing set-up is made up of:

• Two pressed steel housing halves, shaped to hold the spherical outside of an insert bearing
• An insert bearing, usually supplied separately, with an eccentric collar or grub screws to lock it to the shaft
• Mounting holes, in a pillow block, round, oval, or triangular flange layout
• A protective finish, such as galvanising, or stainless steel for wet conditions.

The pressed steel construction keeps the housing light and economical.

• The halves are pressed from sheet steel, so they are much lighter and cheaper than a cast iron housing.
• The shaped centre lets the insert bearing self-align when the housing is bolted down, so small mounting errors are taken up.

Pressed housings are usually sold as housings only, so the insert bearing is chosen and ordered separately.

Why are pressed housings essential?

For light-duty machines, a cast iron housing is often more than the job needs. Pressed housings give a self-aligning shaft support at a fraction of the weight and cost, which makes them ideal for equipment built in large numbers or where weight matters. They bolt straight onto thin sheet metal frames and timber, which would not suit a heavy cast housing.

Because the insert is held between the two halves, a worn insert can usually be replaced by unbolting the housing and fitting a new one, keeping the housing in service.

Typical applications include:

• Light conveyors and roller conveyors
• Agricultural and garden machinery
• Textile and sewing machinery
• Fans and ventilation equipment
• Packaging machinery
• Fitness and leisure equipment
• Timber-framed and sheet metal machinery
• General light industrial equipment

The main types of pressed housings

• Pressed steel pillow block housings - Two-bolt housings with a flat base, for mounting the shaft parallel to a flat surface.
• Pressed steel round flange housings - Three-bolt round flanges, for mounting the shaft at right angles to a panel or frame.
• Pressed steel oval flange housings - Two-bolt oval flanges, for narrow frames and tight spaces.
• Pressed steel triangular flange housings - Three-bolt triangular flanges, for compact and corner-mounted installations.
• Rubber mounted pillow block housings - Pressed steel pillow blocks with a rubber cartridge around the insert, which absorbs vibration and reduces noise.
• Stainless steel pressed housings - Pressed from stainless steel, for washdown, food, and wet or corrosive environments.

Insert bearings for pressed housings include:

• SA inserts - Lock to the shaft with an eccentric collar and grub screw, which grips without marking the shaft. Best for drives that run in one direction.
• SB inserts - Narrower inserts that lock to the shaft with grub screws in the inner ring. Suitable for drives that run in either direction.

How to choose the right pressed housing?

• Insert size - Choose a housing that matches the insert bearing size. Each housing takes inserts of a particular outside diameter, which may cover more than one bore size.
• Shaft size and insert type - Choose an SA or SB insert to suit the shaft diameter, metric or inch, and the locking method you need.
• Mounting style - Choose a pillow block, round, oval, or triangular flange to suit the frame and the direction of the shaft.
• Bolt centres - Check the distance between the mounting holes suits the frame. For example, a PP203 has 68mm bolt hole centres.
• Load and duty - Pressed housings suit light-to-medium loads. For heavier loads or shock, choose a cast iron housing.
• Conditions - Choose galvanised housings for general use, stainless steel for washdown and corrosive conditions, and rubber mounted housings where noise and vibration need to be reduced.

Essential references and specialised ranges

How the numbering works:

Pressed housings are referenced by their style and the insert size they take:

PP = pressed steel pillow block housing

PF = pressed steel round flange housing

PFL = pressed steel oval flange housing

PFT = pressed steel triangular flange housing

SS = stainless steel version, for example SSPP

The number after the letters is the insert size the housing takes, for example PP203 takes SA or SB 201, 202, and 203 inserts.

When a housing and insert are sold together as a unit, the insert type is added at the start:

SAPP206 = pressed pillow block with an SA (eccentric collar) insert for a 30mm shaft

SBPP206 = pressed pillow block with an SB (grub screw) insert for a 30mm shaft

SAPFL206 = pressed oval flange with an SA insert for a 30mm shaft

Some manufacturers, such as RHP, use their own codes for the same housings, for example LPB (pillow block), SLFL (oval flange), and SLFT (triangular flange).

Suffixes:

EC = eccentric collar insert (RHP)

A = grub screw insert (RHP)

-16, -20 and similar = inch bore in sixteenths of an inch

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

FAQ - All you need to know about pressed housings

Is the insert bearing included with a pressed housing?

Usually not. Most pressed housings are sold as housings only, so the insert bearing needs to be ordered separately. Some complete units, such as SAPP and SBPP, come with the insert fitted.

What is the difference between a pressed housing and a cast iron housing?

A pressed housing is made from sheet steel, so it is lighter and cheaper, and suits light-to-medium loads. A cast iron housing is heavier and stronger, and suits higher loads, shock, and vibration.

Which insert bearings fit a pressed housing?

Pressed housings take SA or SB insert bearings of the matching size. One housing size often fits several bore sizes, because the inserts share the same outside diameter. Check the housing reference against the insert size before ordering.

Do pressed housings need lubrication?

The housing itself does not need lubrication. The insert bearings used in pressed housings are usually greased and sealed for life. In dirty or wet conditions, check them regularly and replace the insert if it becomes rough or noisy.

How do I fit a pressed housing?

Place the insert bearing between the two housing halves and bolt them loosely to the frame. Slide the shaft through, line everything up, and tighten the bolts evenly so the housing is not distorted. Lock the insert to the shaft last, once the shaft turns freely.

How do I identify a pressed housing I need to replace?

The reference is usually stamped on the housing. If it cannot be read, measure the bolt hole centres, the bolt hole size, and the overall size of the housing, and check the size marked on the insert bearing. Also note the mounting style and whether the housing is galvanised or stainless.

What are the signs that a pressed housing needs replacing?

Look out for:

• A bent, cracked, or rusted housing
• Loose mounting bolts or elongated bolt holes
• The insert bearing moving or rattling in the housing
• Grinding or squealing from the insert bearing
• Play in the shaft
• The shaft slipping in the insert