Bracket Housings

What is a bracket housing?

A bracket housing, also called a bracket flange or three-bolt bracket flange, is a compact bearing housing with three bolt holes, designed to bolt a shaft support straight onto a machine frame or panel. Like other insert bearing housings, it holds a self-aligning ball bearing insert ready to fit, but its three-bolt bracket shape gives a secure fixing in less space than a square four-bolt flange.

A standard bracket housing unit is made up of:

• A cast iron bracket flange with three bolt holes
• A self-aligning insert bearing, seated in a spherical bore in the housing
• A locking method, usually grub screws, that fixes the insert to the shaft
• Seals on both sides of the insert bearing.

The three-bolt bracket shape is the key feature.

• Three fixing points give a stable, triangulated mounting that resists rocking, while keeping the housing compact.
• The narrow body suits light frames, small machines, and places where a larger flange would not fit.

Bracket housings are available as complete units with the insert fitted, or as housings on their own.

Why are bracket housings essential?

Bracket housings are a neat, practical answer for supporting small and medium shafts on light frames. Three bolts give a firmer fixing than a two-bolt oval flange, but the housing stays small and light, which makes it popular on agricultural machinery, light conveyors, and general equipment where weight and space matter.

As with other insert bearing units, the spherical seat lets the bearing align itself as it is bolted down, so it copes with small errors in the frame. Standard metric and inch sizes make replacements easy to find.

Typical applications include:

• Light conveyors and roller supports
• Agricultural machinery and implements
• Material handling equipment
• Light-to-medium industrial machinery
• Garden and grounds equipment
• Packaging machines
• Automotive and vehicle component mounting
• Fitness and leisure equipment

The main types of bracket housings

• Cast iron bracket flange units - The standard design, with a strong cast iron three-bolt housing and a grub screw locking insert. They suit most light-to-medium duty applications.
• Pressed steel three-bolt flanges - These are made from two pressed steel plates clamped around a narrow insert bearing. They are very light and low in cost, and suit light-duty equipment.
• Bracket flange units with stainless inserts - A cast iron bracket housing fitted with a stainless steel insert bearing, for better resistance to moisture and corrosion.
• Stainless steel and thermoplastic bracket housings - Fully corrosion-resistant versions, for food processing, washdown, and wet environments.
• Metric and inch bore units - Bracket housings are widely available in both metric and inch shaft sizes.

Locking options include:

• Grub screws - The standard method on most bracket units. Easy to fit and suitable for drives that run in both directions.
• Eccentric collars - Used on some units, especially pressed steel types. They grip the shaft without marking it, but are best suited to drives that run in one direction.

How to choose the right bracket housing?

• Shaft size - Match the insert bearing bore to the shaft, and check whether the shaft is metric or inch.
• Mounting space and bolt pattern - Check the bolt centres, overall length, width, and height of the housing suit the frame. Three-bolt patterns differ between housing types, so measure the existing holes if you are replacing a unit.
• Load - Bracket housings suit light-to-medium loads. For heavier loads or vibration, a square four-bolt flange or pillow block is usually a better choice.
• Material - Choose cast iron for general use and pressed steel for light duty. For damp or corrosive conditions, choose a stainless insert or a fully stainless or thermoplastic unit.
• Locking - Grub screws suit most applications. Choose an eccentric collar insert if the shaft must not be marked and the drive runs in one direction.

Essential references and specialised ranges

How the numbering works:

Bracket housing unit references combine the insert bearing and the housing:

UC = insert bearing with grub screw locking and an extended inner ring

FB = three-bolt bracket flange housing

The digits = the series and bore code. Multiply the last two digits by five to get the bore in mm, from 04 upwards. Smaller sizes use 01 = 12mm, 02 = 15mm, and 03 = 17mm.

Examples:

UCFB202 = bracket flange unit for a 15mm shaft

UCFB204 = bracket flange unit for a 20mm shaft

UCFB205 = bracket flange unit for a 25mm shaft

Inch bore units add a suffix showing the bore in sixteenths of an inch:

UCFB201-8 = 1/2 inch shaft

UCFB202-10 = 5/8 inch shaft

UCFB204-12 = 3/4 inch shaft

UCFB205-16 = 1 inch shaft

Pressed steel three-bolt flanges use their own references, often based on the insert type and flange size.

Suffixes:

-8, -10, -12, -16 and similar = inch bore in sixteenths of an inch

E = eccentric collar locking insert

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

FAQ - All you need to know about bracket housings

What is the difference between a bracket housing and other flange housings?

A bracket housing has three bolt holes, which gives a firmer fixing than a two-bolt oval flange but takes up less space than a four-bolt square or round flange. It is a good middle ground for light-to-medium loads on compact frames.

Is a bracket housing the same as a three-bolt flange?

The names are often used for the same thing. Cast iron three-bolt units are usually called bracket flanges, while pressed steel three-bolt flanges are made from two plates and hold a narrower insert bearing.

Can I fit a bracket housing at an angle?

Yes. The housing can be bolted to any flat face, so the shaft can be horizontal, vertical, or at an angle, as long as the mounting face is square to the shaft.

Do bracket housings need lubrication?

The insert bearing is supplied greased and sealed. Some bracket units have a grease nipple for relubrication, while others are lubricated for life. In dusty or wet conditions, units that can be regreased will usually last longer.

How do I fit a bracket housing?

Slide the unit onto the clean, burr-free shaft, fit the three bolts, and tighten them evenly so the housing sits flat against the frame. Once both ends of the shaft are bolted down and the shaft turns freely, tighten the grub screws or lock the collar onto the shaft.

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

The reference is usually cast on the housing and marked on the insert bearing. If it cannot be read, measure the shaft diameter, the bolt centres, the bolt hole size, and the overall length, width, and height of the housing. Also check whether the housing is cast iron or pressed steel.

What are the signs that a bracket housing needs replacing?

Signs to watch for include:

• Noise from the bearing, such as grinding or squealing
• More vibration than normal
• The housing feeling hot
• Play or wobble in the shaft
• Grease or dirt around the seals
• A cracked or bent housing, or loose bolts
• The shaft slipping in the insert bearing