POGGI Flexible Shaft Coupling Ranges

The POGGI selection of flexible shaft coupling designs all serve the fundamental purposes of connecting driving & driven shafts, accommodating misalignments and absorbing shocks. This may be simply to extend the drive line, or more frequently to connect ‘Prime Movers’, such as electric motors (predominately), hydraulic motors, or engines, etc., via their output shaft, to ‘Driven Machines’, such as pumps, compressors, gearboxes, rolls, Line shafts, presses, fans, stirrers, pulleys, sprockets, etc., via their input shafts.

The design flexibility of the coupling connection accommodates small misalignments – radial, angular & axial – between the coupling input & output shafts. The GDR Nylon Sleeve design provides a simple, low friction, low weight, competitively priced, maintenance-free, gear coupling connection for shafts up to 65mm diameter & torques up to 350Nm; whereas, the GDA All-steel gear coupling design requires lubrication, but can transmit much higher torques (up to 55,000Nm).

The GH ‘Spider’ coupling, however, is ‘fail-safe’, as it has interlocking cast iron jaws that will prevent ‘freewheel’ & still drive, should the flexible gear ring ‘spider’ interlocking teeth be damaged. The GS Chain coupling, however, offers a very high torque capacity, but this is only offered inclusive of the LC Sprocket Friction-Clutch.

GDR flexible shaft couplings (with NYLON SLEEVES): comprise of 2 solid steel hubs, each with external gear teeth one end, coupled by means of a 6.6 Polyamide Nylon Outer Sleeve, with internally moulded straight teeth. The hub teeth are both crowned & barrelled, thereby eliminating edge pressures, on misalignment, minimising tooth reactive forces and providing for radial, angular & axial misalignment accommodation.

They are of compact design, with a high torque transmission capacity, relative to their size & weight. The steel & Nylon tooth engagement combination provides a low friction characteristic, which consequently eliminates both wear and the need for lubrication and maintenance. Continuous operating temperatures from -25ᴼC to +90ᴼC, with short periods of up to +125ᴼC are permissible. [Higher temperature Sleeve material details, on request].

Both Standard & Extended length Hubs are available in all sizes, making 3 coupling length variations possible for each size. Standard Hubs are stocked, either un-bored, or with imperial & metric finish bores & Keyways (Please enquire for details). These cover:

  • 14mm to 65mm diameter shafts
  • transmission torques from 6Nm to 350Nm

The couplings are also electrically isolating.

GDA Flexible Gear Couplings (with STEEL SLEEVE)

Whilst also comprising of 2 solid steel hubs, each with external gear teeth one end, but coupled by means of a solid steel outer Sleeve, with internal straight teeth, (just like the GDR), but instead, sealed at each end by a single lip Nitrile seal, both retained by a circlip. The sleeve is machined from R80-90 kg/sq. mm grade steel, whilst the hubs are machined from carbon steel with the teeth being high frequency hardened. Both sleeve and hubs are machined all over, making the coupling especially suitable for high speed applications, as the parts are in perfect dynamic balance.                              

The hub teeth are both crowned and barrelled, then accurately machined to ensure that clearances between the meshing teeth are kept to a minimum, without limiting the flexibility required to accommodate radial, angular & axial shaft misalignments. However, they require continuous grease lubrication, which can be charged via the special re-grease plug hole located in the sleeve, which also acts as an end stop for each hub. The Nitrile rubber lip seals, retained by circlips, ensure a positive seal to the sleeve chamber.

Both Standard & Extended length Hubs are available in all sizes, making 3 coupling length variations possible for each size. Standard Hubs are stocked un-bored. The range covers:

–  from 28mm to 200mm diameter shafts

–  transmission torques from 210Nm to 55,000Nm

GH ‘Spider’ Couplings:

The Range covers the more common standard span of IEC electric motors. They comprise of 2 congruent G20 cast-iron hubs, with concave shaped dogs at the inner end, arranged in semi-segments next to each other around the circumference, so that a convex toothed flexible ‘spider’ can be inserted in the free space between them.

The hubs are finish-machined over all surfaces for increased service life. Individual teeth of the connecting ‘spider’ element have a barrelled profile in order to eliminate edge pressures when shafts are misaligned, thereby compensating for radial & angular misalignments.

Spiders are manufactured from a polyurethane elastomer of 94° Shore hardness – which is highly resistant to wear, oil, acids, ozone and ageing. The Spider Couplings are torsionally flexible, transmitting torque undistorted, dampening shocks & oscillations, or absorbing vibrations.

High internal damping by the spider protects the drive against dynamic overload. Its exponential curve characteristics enable fast reduction of oscillation energy & limits vibration amplitude. The spider teeth are not involved in any bending wear, being only subject to pressure, with the load being shared between each tooth.

They can operate in a temperature range of -30°C to + 80°C, or up to +120ᴼC for brief periods.

The Range covers:

  • Shafts up to 90mm diameter
  • Torques up to 2,454Nm

LC Friction-Clutch Torque Limiter

Designed to provide a simple, but effective overload protection, during operation – to both’ prime mover’ – on the input side, and radially driven, mechanical components, on the output side. It is recommended for limiting start-up overloads, temporary load peaks and excess reversal loading, in order to prevent damage to motors and transmission components, such as belt or chain drives, gears etc. They are generally used on machinery or equipment that requires a reliable safety device.

The material used for the manufacture of the friction plates does not contain asbestos.

The construction of the LC Torque Limiters provides for their use with the following transmission components that POGGI can also supply:

  • Timing pulleys
  • Chain sprockets and wheels
  • V-belt pulleys
  • Gears

The unit to be connected is held between the friction plates, which are secured by rotating the nut. The pressure exerted from the nut, via the springs, generates the necessary friction force. This is altered by adjustment of the nut tightening torque.
Once the correct Limiter type has been selected and the lock nut tightened accordingly, there should be no slippage between the driving unit and the limiter itself, during ‘normal’ operation of the transmission, i.e. a rigid drive.

However, on overloading, the driving unit slips across the friction plates in the Torque Limiter, thereby restricting the torque transmitted and the drive is immediately disconnected. However, when the overload ends, the drive is automatically re-engaged, with no need for any external action.

LC Torque Limiters can be used both in ‘dry’ operating conditions, or immersed in an oil bath. When used in oil soaked conditions, a 25% drop in the torque transmission capacity has to be allowed for. In case of an oil bath, it is necessary to first dip the friction plates into oil type, SAE30, before mounting:

  • 5 Sizes, with 10 alternative Torque Limit Options
  • For 10-1250 Nm torque transmission capacity
  • Shaft sizes from 24mm to 65mm diameter
[N.B. For alternative, Spring-Loaded Detent Balls Safety Overload Clutch couplings – See our KBK Products]

GS Safety Chain Coupling with LC Limiter

GS safety couplings are units that combine the need for coaxial connection between two shafts, whilst at the same time, having the ability to protect transmission components linked through the coupling from temporary overloads. It is an assembly consisting of a standard LC Torque Limiter, with one plate wheel of a duplex type chain sprocket serving as the centre member, held between the friction plates and the other formed into the other shaft hub. Thus, driving and driven sides are coupled via a duplex type roller chain. Coupling sizes align with the GS Torque Limiter Range, with applications and function, also following their design features.