How shaft-hub connections have evolved

Engineers have explored many ways to make shaft-hub connections over the years and this present article explores the evolution to the hydraulic type that is now considered by many to be the state of the art.

Today three types of shaft-hub connection are commonly used by machine builders, namely keyways, mechanical connections and hydraulic clamps. We will consider each type in turn.

Image

Keyway connections

A keyway connection consists of a slot cut in a shaft component, receiving part of a key that also engages with an equivalent slot on a mating hub component, thereby locking the two parts together.

Image

While keyways are cheap to produce and well standardised, disadvantages include:

  • Disadvantageous for mounting, dismounting and adjusting
  • As forces are concentrated around a small area, bigger shafts are needed to transmit torque{
  • ] which results in over-dimensioning
  • Increased inbalance and weaker precision of the mounted shaft and components
  • Prolonged, meticulous assembly required, as the exact location of the keyway needs to be established
  • Keyways weaken shafts, causing an increased risk of fretting, fatigue and breakage

Mechanical connections

Mechanical clamping connections consist of two sleeves with tapered surfaces that are pressed against each other along the shaft. Many screws with a high tightening torque are used to hold it together. When mounted the two sleeves deform into contact with the bore of the hub and the surface of the shaft. This technique is used in rough applications where surfaces finish and tolerances are variable.

Image

While this standard connection is suitable for transmitting high radial loads, bending torque and can withstand temperature variations, disadvantages include:

  • Sleeves move axially, making hub positioning difficult
  • High tightening torque required on screws to overcome internal friction forces on tapered sleeves
  • Difficult to get good runout; screws must be tightened evenly and in a certain pattern
  • Special dismantling screws are needed to overcome internal friction between sleeves and to release the connection
  • Disadvantageous for mounting, dismounting and adjustment

Hydraulic clamping connections

Hydraulic clamping connections enable effortless mounting, adjustment, easy reach and a well-balanced design. The technique is a problem-solver for critical applications. ETP hydraulic clamping connections are beneficial for working with tight tolerances, resulting in superior runout.

Image

French scientist Blaise Pascal devised the maxim of pressure propagation in liquids during the 17th century. The principle refers to pressure changes in a liquid within a confined container where pressure transmits evenly throughout the liquid. When applying pressure at one point of the liquid, an even pressure change occurs throughout the whole container (see below).

Image

ETP hub-shaft connections are guided by Pascal's principle. The products consist of hardened double-walled steel sleeves that are welded together to create a hollow chamber; this chamber is filled with a hydraulic pressure medium.

How a hydraulic clamping connection works

Image
By the low force of your hand tightening the screw, an internal pressure of approximately 1000bar is created. This causes the sleeves to expand evenly in all directions around the hub and shaft. The result is an even surface pressure and a secure and precise connection between the hub and shaft.

By using the ETP principle, a hydraulic shaft-hub connection offers a number of advantages compared to the alternatives:

  • Easy and accurate positioning along the shaft, as no axial movement occurs during tightening
  • Mounting and dismounting takes seconds
  • Excellent runout as the connection self-centres
  • Compact, with small built-in dimensions
  • Free space along the shaft as there is no need for dismantling screws or special tools

Image

Quick, easy, precise

Image
ETP is said to be the only company manufacturing a standard range of hydraulic hub-shaft connections. These hydraulic connections create an even surface pressure around the hub and shaft. Mounting and dismounting of ETP connections takes only a matter of seconds. Furthermore, ETP hydraulic connections achieve excellent runout because they are self-centring.

Available through Abssac, this is a truly innovative product. All ETP products consist of a double-walled hardened steel (in some cases stainless steel) sleeve, filled with a pressure medium. Within the connection flange there are one or more screws and a piston with seals for the pressure setting. When the pressure screw is tightened an even and moderately high surface pressure is created against the shaft and hub, causing the locking effect. The self-contained product allows the clamping procedure to be repeated many times. Whether the hubs are to be removed or repositioned, mounting and dismantling takes only a few seconds. The hydraulic principle gives immediate advantages for today's machine builders.

Follow the link for more information about ETP hydraulic shaft-hub locking bushes from Abssac.

Abssac

E1A The Enterprise Centre
Enterprise Way
Evesham
WR11 1GS
UNITED KINGDOM

+44 (0)1386 421005

sales@abssac.co.uk

www.abssac.co.uk

More from Abssac

ETP-EXPRESS hydraulic bushes are quick to mount and dismount

Posted 2 weeks ago

Metal bellows - an enabling technology for many applications

Posted 6 months ago

Everything you need to know about lead screws

Posted 7 months ago

Movie of the month

Posted 8 months ago

Abssac virtual and interactive exhibition is open all hours

Posted 8 months ago

Standard and custom miniature precision lead screws

Posted 8 months ago

Movie of the month

Posted 1 year ago

High-precision satellite roller screws from a UK source

Posted 1 year ago

Compact torque limiters protect critical equipment

Posted 1 year ago

Ball screws and lead screws from stock or fully customised

Posted 1 year ago

Reliable emergency braking and holding during power outages

Posted 2 years ago

Movie of the month

Posted 2 years ago

Miniature safety brakes are super-slim and energy-efficient

Posted 2 years ago

Movie of the month

Posted 3 years ago

Expertise in rotary products

Posted 3 years ago

Abssac to distribute Helix Linear Technologies' products in UK

Posted 3 years ago

Movie of the month

Posted 3 years ago

An insider's view of Abssac's precision linear products

Posted 3 years ago

Movie of the month

Posted 4 years ago

A day in the life of Abssac - experts in precision motion

Posted 4 years ago

How to select the right shaft coupling for a rotary encoder

Posted 4 years ago

Movie of the month

Posted 4 years ago

Abssac's miniature ball screws at the Engineering Design Show

Posted 4 years ago

How machined springs out-perform wire-wound springs

Posted 4 years ago

Spinplus shaft coupling suits highly dynamic applications

Posted 4 years ago

Carbon Composite Bellows Springs provide compressive tunability

Posted 4 years ago

Movie of the month

Posted 6 years ago

Extension and compression springs machined from solid material

Posted 6 years ago

Movie of the month

Posted 6 years ago

Schmidt-Kupplung shaft couplings handle severe parallel offsets

Posted 6 years ago

Machined springs meet the needs of downhole measurement system

Posted 6 years ago

Movie of the month

Posted 6 years ago

Movie of the month

Posted 6 years ago

Shaft-hub connection saves set-up time on food conveyor

Posted 6 years ago

Satellite roller screw from Abssac

Posted 6 years ago

Stainless steel Schmidt-Kupplung shaft couplings

Posted 6 years ago

Movie of the month

Posted 7 years ago

Precision miniature cold rolled lead screws and nuts

Posted 7 years ago

Machined compression and extension spring replaces wire spring

Posted 7 years ago

Custom-designed flexible beam coupling for encoder application

Posted 7 years ago

Semiflex precision offset couplings used in glass coating system

Posted 7 years ago

Movie of the month

Posted 7 years ago

Miniature lead screws are cost-effective and high-performance

Posted 7 years ago

Self-reversing machined screws manufactured to order

Posted 7 years ago

Precision ball screws used in electronic microscope

Posted 7 years ago

ETP-POWER shaft-hub connection achieves higher clamping loads

Posted 8 years ago

Edge-welded bellows used in NASA's cryogenic chambers

Posted 8 years ago

Movie of the month

Posted 8 years ago

ABSSAC Movie

Posted 8 years ago

Constant-velocity shaft couplings for encoder applications

Posted 8 years ago

Easy-to-use ETP hydraulic hub-shaft connections from Abssac

Posted 8 years ago

High-accuracy springs for high temperatures

Posted 8 years ago

Shaft couplings match the needs of printing machinery

Posted 8 years ago

Movie of the month

Posted 8 years ago

Shaft coupling used for aerator device in oxygenation of water

Posted 8 years ago

Ball screws, trapezoidal screws and satellite roller screws

Posted 8 years ago

Semiflex shaft couplings suit large parallel shaft offsets

Posted 8 years ago

Movie of the month

Posted 9 years ago

Jaw shaft couplings stocked with pre-machined bores and keyways

Posted 9 years ago

Movie of the month

Posted 9 years ago

Schmidt-Kupplung shaft couplings available from Abssac

Posted 9 years ago

Custom split nut reduces machine cycle time

Posted 9 years ago

Lead screw and nut assemblies for high-vacuum applications

Posted 9 years ago

Miniature lead screw provides precision and reliability

Posted 10 years ago

Movie of the month

Posted 10 years ago

Movie of the month

Posted 10 years ago

Shaft couplings supplier offers extensive range plus expertise

Posted 10 years ago

Ball screw supplier offers wide choice and competitive prices

Posted 10 years ago

Plastic ball screw and nut assembly in a choice of polymers

Posted 10 years ago

Pitch preparation advice and tips from Abssac

Posted 10 years ago

Movie of the month

Posted 10 years ago

Motion products backed up by expert technical support

Posted 10 years ago

Helical Flexures compensate for high angular misalignment

Posted 10 years ago

Pancake-shaped compression springs machined from solid

Posted 10 years ago

Abssac contact details change with move to new premises

Posted 10 years ago

Machined torsion springs offer advantages over wire types

Posted 11 years ago

Sure-Flex elastomeric shaft couplings are maintenance-free

Posted 11 years ago

Movie of the month

Posted 11 years ago

Miniature ball screws: precision standard or custom units

Posted 11 years ago

Movie of the month

Posted 11 years ago

Ball screws and nuts for machine tool refurbishment

Posted 11 years ago

Movie of the month

Posted 11 years ago

Satellite roller screws and their inherent advantages

Posted 11 years ago

Shaft couplings used in one-piece, multi-functional components

Posted 11 years ago

Ball screws offer advantages of rolled and ground types

Posted 11 years ago

Trapezoidal lead screws from stock, with free cutting service

Posted 11 years ago

The benefits of helical beam shaft couplings

Posted 11 years ago

Movie of the month

Posted 11 years ago

Test movies for abssac

Posted 11 years ago

Choosing lead screws, ball screws and satellite roller screws

Posted 11 years ago

Movie of the month

Posted 11 years ago

Helical flexure used in self-aligning, long-life die cutter

Posted 12 years ago

Atherm bellows compensate for temperature changes

Posted 12 years ago

Budgetbeam shaft coupling offers high torsional stiffness

Posted 12 years ago

Abssac website includes new products and animations

Posted 12 years ago

Acme and trapezoidal lead screws from a UK supplier

Posted 12 years ago

Bespoke lead screws and nuts manufactured to order

Posted 12 years ago

Cut the cost of precision ball screws

Posted 12 years ago

Budgetbeam flexible shaft couplings available to buy online

Posted 12 years ago

How flexible is your supplier of shaft couplings?

Posted 12 years ago

What are the advantages of machined springs?

Posted 12 years ago

Ultra-fine-pitch lead screws for precise movements

Posted 12 years ago

Deck gear couplings and Sier Bath Deck gear couplings

Posted 12 years ago

Roller screws deliver four-times higher thrust

Posted 12 years ago

UK source for TB Wood's power transmission products

Posted 12 years ago

More sizes of lead screw, acme thread and ball screw

Posted 12 years ago

Self-reversing lead screws manufactured in short lead times

Posted 12 years ago

Helical beam drive combines three parts in one

Posted 12 years ago

Miniature ball screws are diameter 1.8mm

Posted 12 years ago

Free shaft couplings for test purposes

Posted 12 years ago

Customised lead screws are economical for linear motion

Posted 12 years ago

Electroformed spring contacts provide reliable connections

Posted 12 years ago

Stainless steel ball screws are precise and cost-effective

Posted 12 years ago

Abssac wins Pharmatex innovation award

Posted 12 years ago

Double-handed lead screws need no lubrication

Posted 12 years ago

Edge-welded bellows deliver flexibility in a compact package

Posted 12 years ago

Couplings help cut energy consumption - and carbon footprint

Posted 13 years ago

Splined shafts available in very large sizes

Posted 13 years ago

Bi-directional ball screws move nuts in opposite directions

Posted 14 years ago

Leadscrews offered with custom nuts for standard prices

Posted 14 years ago

Advantages of electrodeposited nickel bellows and electroforms

Posted 14 years ago

Satellite roller screws offer benefits over ball screws

Posted 14 years ago

More technical articles
6 hours ago
Certified Machinery Safety Expert course on 18th January
In conjunction with TÜV NORD, Pilz Automation UK is hosting its first CMSE Course of 2021. It starts on 18th January and lasts for four days
8 hours ago
Improving communication with (and between) machines
Lenze has published a White Paper discussing PackML, a programming standard defined by OMAC, the Organisation for Machine Automation & Control. Here, Lenze's Marc Vissers provides machine builders with an insight into the paper
9 hours ago
Danfoss buys Artemis Intelligent Power
Danfoss says it will allow them to begin the global commercial rollout of its Digital Displacement® pump technology, a disruptive low-carbon opportunity with applications in the industrial and off-highway markets
1 day ago
Quarter turn fastener that still turns heads
Automotive manufacturers are gradually making the transition from solely manufacturing vehicles to taking on more responsibility for the performance of a vehicle over its life cycle. As a result, OEMs are increasingly looking for ways to lower installation costs, and facilitate quick repeatable access to critical vehicle components in order to enable faster service calls
1 day ago
Wave spring or coil spring?
Simon Ward is Technical Manager at Uckfield-based fastener specialists TFC. Here he offers a machine designers a comparison between wave springs and round wire coil springs 
1 day ago
New course: Safety Design Incorporating EN ISO 13849-1/EN 62061
Pilz Automation UK says that this training course is designed to enable delegates to develop a greater understanding of the processes and standards related to safety control system specification, design and validation
2 days ago
Intelliconnect moves to larger factory as sales grow
Intelliconnect (Europe) Ltd has moved to a larger facility at the Corby Innovation Hub
2 days ago
ABB industrial robots get Wizard programming
ABB is expanding it Wizard easy programming tool to encompass its industrial robot range, saying that it makes robots easier to install, programme and operate without specialised training
2 days ago
New Siemens Sivacon S8 Power Partner appointed
Nottingham-based manufacturer of bespoke LV control systems Blackburn Starling has become a Siemens Sivacon S8 Power Partner
2 days ago
Drive systems enhance rehabilitation technology
maxon Group and Fourier Intelligence have announced a global partnership. maxon's precision drive systems and Fourier' Intelligence rehabilitation robotics will combine in the development of new technologies for patients