Take Up Units

What is a take-up unit?

A take-up unit is a bearing housing that can slide along a frame, so the position of a shaft can be adjusted. It is used to tension belts, chains, and conveyor belts by moving the shaft, and the pulley or sprocket on it, closer to or further from the drive. Once the tension is set, the housing is held in place by an adjusting screw, so the shaft stays exactly where it is needed.

A standard take-up unit is made up of:

• A take-up housing with machined slots or guides on each side, which slide in a frame or channel
• A self-aligning insert bearing, held in a spherical seat in the housing
• A threaded hole or boss for an adjusting screw, which pushes or pulls the housing along the frame
• A locking method that fixes the insert to the shaft, plus seals and a grease nipple.

The sliding design is what makes take-up units so useful.

• The housing moves along the frame while the shaft stays parallel, so belt and chain tension can be adjusted quickly and evenly.
• As belts stretch and chains wear in service, the unit can be moved again to restore the correct tension, without removing anything.

Take-up units can be bought as complete units with the insert fitted, as a housing on its own, or with a matching steel frame and adjusting screw.

Why are take-up units essential?

Belts and chains only work properly at the right tension. Too slack, and they slip, jump, or wear quickly. Too tight, and they overload the bearings and shafts. A take-up unit gives a simple, built-in way to set the tension when a machine is installed and to adjust it as the belt or chain stretches over time.

On conveyors, take-up units are usually fitted at the tail pulley, where they also keep the belt tracking straight. Using a pair of units, one at each side, the pulley can be moved squarely, or one side can be adjusted slightly to correct a belt that runs off to one side. The self-aligning insert bearings make this easy, as they cope with small angle changes as each side is adjusted.

Typical applications include:

• Conveyor tail and return pulleys
• Belt and chain drives
• Screw conveyors and bucket elevators
• Agricultural machinery
• Food processing and packaging lines
• Quarrying and aggregate equipment
• Woodworking and sawmill machinery
• Textile and printing machines

The main types of take-up units

• Cast iron take-up units - The most common design. The housing has guide slots on each side, which slide in a channel or between guide rails, and a boss for the adjusting screw.
• Take-up units with frames - The housing is supplied with a matching steel frame and adjusting screw as a complete assembly, ready to bolt to the machine. They come in different frame lengths to give more or less adjustment travel.
• Wide slot take-up units - These have wider guide slots to suit heavier frames or channels.
• Heavy-duty take-up units - These take a larger 300 series insert bearing, for heavier loads on the same shaft size.
• Pressed steel take-up units - Lighter and lower in cost, for light-duty conveyors and drives.
• Stainless steel and thermoplastic take-up units - For food processing, washdown, and wet or corrosive conditions.

Locking options include:

• Grub screws - Simple and suited to most applications, including drives that run both ways.
• Eccentric collars - Grip without marking the shaft, and are best for drives that run in one direction.

How to choose the right take-up unit?

• Shaft diameter - Choose an insert bearing that matches the shaft diameter, and check whether the shaft is metric or inch.
• Adjustment travel - Work out how far the shaft needs to move to fit and tension the belt or chain, and allow extra for stretch over its life. Choose a frame length that gives enough travel.
• Frame or guides - If you already have a channel or guide rails, check the slot width and guide dimensions of the housing match. If not, a take-up unit with its own frame is the simplest option.
• Load - Consider the belt or chain tension as well as the weight of the pulley and load. For heavy duty, choose a 300 series unit.
• Conditions - For washdown, food, or wet environments, choose stainless steel or thermoplastic units.

Essential references and specialised ranges

How the numbering works:

Take-up unit references combine the insert bearing and the housing:

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

T = take-up housing

The digits = the series and bore code. 2 is the standard series and 3 is the heavier series. Multiply the last two digits by five to get the bore in mm.

Examples:

UCT204 = take-up unit for a 20mm shaft

UCT206 = take-up unit for a 30mm shaft

UCT210 = take-up unit for a 50mm shaft

T206 = the take-up housing on its own, which takes a UC206 insert

Inch bore units add a suffix showing the bore in sixteenths of an inch, so a UCT205-16 fits a 1 inch shaft.

Take-up frames are usually listed separately, with their own references for each housing size and frame length.

Suffixes:

E = eccentric collar locking insert

-16, -20, -24 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 take-up units

What does a take-up unit do?

It holds the bearing for a shaft and lets it slide along a frame, so you can move the shaft to tighten or loosen a belt or chain. Once set, the adjusting screw holds it in place.

How do I adjust a take-up unit?

Loosen any locking nuts, then turn the adjusting screw to move the housing along the frame until the belt or chain is at the correct tension. On a pair of units, adjust both sides by the same amount to keep the shaft square, then tighten the locking nuts.

How can I use take-up units to correct belt tracking?

If a conveyor belt runs off to one side, adjusting one take-up unit slightly can steer it back. Make small adjustments, let the belt run for a few turns after each one, and check the tracking before adjusting again.

Do take-up units need lubrication?

Yes. The insert bearing is supplied greased, and most units have a grease nipple for relubrication. The adjusting screw and guide slots should also be kept clean and lightly greased, so the housing slides freely when it needs adjusting.

How do I fit a take-up unit?

Slide the housing into the frame or guides, fit the adjusting screw, and slide the unit onto the clean, burr-free shaft. Set the tension with the adjusting screw, check the shaft is square, and then lock the insert to the shaft. Recheck the tension after the machine has run for a short time.

How do I identify a take-up unit 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 width across the guide slots, the slot width, and the overall height and length of the housing. If it has a frame, also measure the frame length and adjusting screw size.

What are the signs that a take-up unit needs replacing?

Look out for:

• Noise, grinding, or squealing from the bearing
• Increased vibration or the shaft running out of true
• The housing running hot
• Play in the shaft
• Grease leaking past the seals
• The housing sticking or binding in the frame
• A damaged adjusting screw or cracked housing