Twiflex M1429 User manual

M1429
INSTRUCTION MANUAL
for
REMOVAL AND INSTALLATION
of
BLOCK AND SLEEVE
ASSEMBLIES
for
LAYRUB COUPLINGS

i
AMENDMENT RECORD
M1429
Amendment
Number Issue Date Signature
- 01 February 2004 -

M1429
Sheet 1 of 8 Issue 01
February 2004
INTRODUCTION
Layrub couplings have been used in the power transmission industry for over 60 years.
Industrial uses are wide and varied. They included Railways, Trams, Buses, Marine Propulsion,
Auxiliary Drives, Earth Moving Equipment, Aero Industry, Steel Works, Oil Refineries, Mining,
Automotive, Offshore Exploration, Engine Testing, Cooling Towers, Power Generation and
Cement Works.
They provide a connection between a driving and driven machine, which absorbs shock loads,
reduces noise, operates in hostile environments, can accept high levels of misalignment and is
very cost effective.
For engine drive applications they provide damping and are particularly suitable for the control
of torsional vibration.
LAYRUB PRINCIPLE (THE LAYRUB BLOCK)
The bore of the resilient block is reinforced by a high tensile steel wire screen formed from wire
cloth wound tightly round a mandrel and secured by cold soldering. The screen is located in the
mould and vulcanised under pressure causing the rubber to penetrate the wire screen and form a
secure bond. The canvas bonded to the outside diameter of the resilient block is to preserve
dimensional stability only.
The composition of the rubber is of special mix having low heat build up characteristics to cater
with the rapid deformations encountered in service.
For attachment to suitable driving flanges, steel sleeves are pressed into the screen of the resilient
block. The sleeves are shouldered, with spigots to suit mating counterbores in the flange, and the
whole being finally clamped by a bolt and nut.

M1429
Sheet 2 of 8 Issue 01
February 2004
THE LAYRUB BLOCK

M1429
Sheet 3 of 8 Issue 01
February 2004
TYPE OF LAYRUB COUPLINGS
The Layrub coupling is produced in various types and sizes, each type being specially
designed to fulfil a particular combination of operating conditions, all the couplings
have resilient blocks exactly as previously described.
TWO - FOUR SERIES
THREE - SIX SERIES
SIX - SIX SERIES

M1429
Sheet 4 of 8 Issue 01
February 2004
INSPECTION
At planned maintenance or shutdown, a routine inspection of the Layrub coupling should be made.
Check for signs of bolt slackness and cracks on the rubber surface of the resilient block.
The difference between cracks and creases may at first prove a little difficult to distinguish but a
coupling can be condemned prematurely because of a wrong assumption.
The resilient block is fitted into the housing bore under compression and the added torque load
further compresses the drive side of the block. In time, the profile of the rubber creases similar to a
fold in the human skin. A crack on the other hand penetrates the body of the rubber and may after
further development cause damage to the coupling. With a suspected crack therefore use a blunt tool
(e.g. small screwdriver) to probe the area and ascertain the extent of the flaw. Cracks which
penetrate below the surface of the rubber indicate that the coupling should be replaced. Examine the
bonding of the screen to the rubber and if failure at this point is apparent, new block and sleeves
should be fitted.
High operating temperatures may cause the rubber profile to develop numerous hairline cracks
giving a crazy surface. This is of no consequence unless the rubber surface has become hard and
brittle, in which case the rubbers should be renewed.
Examination of a coupling on the bench is best carried out by inserting a bar into the sleeve and
levering the block slightly off centre to work the profile of the rubber.
REPLACEMENT OF BLOCK AND SLEEVE ASSEMBLIES
An exchange repair service operates in Great Britain and in some overseas territories but where such
a scheme is impracticable, the servicing procedure for Layrub couplings is as follows:-
1. Remove the damaged block and sleeve assemblies from the housing by hand or hydraulic
press.
2. Ensure that the housings pockets are thoroughly clean and free from all burrs.
3. Locate the new block and sleeve as shown in the assembly drawing (sheets 5 & 6) and coat
the outer diameter with a liberal quantity of commercial vaseline.

M1429
Sheet 5 of 8 Issue 01
February 2004
Assembly of Resilient
Block and Sleeve Unit
Into an Open Pocket Housing
RAM
INVERTED
SUPPORT
RESILIENT BLOCK
TO BE COATED
WITH YELLOW
COMMERICAL
VASELINE BEFORE
INSERTION INTO
THE HOUSING
HOUSING

M1429
Sheet 6 of 8 Issue 01
February 2004
Assembly of Resilient
Block and Sleeve Unit
Into a Closed Pocket Housing
RAM
HOUSING
VENTURI
BLOCK & SLEEVE
RESILIENT BLOCK
TO BE COATED
WITH YELLOW
COMMERICAL
VASELINE BEFORE
INSERTION INTO
THE VENTURI

M1429
Sheet 7 of 8 Issue 01
February 2004
NOTE
ON NO ACCOUNT SHOULD GREASE BE USED AS A MEANS OF LUBRICATION.
4. Ensure that the housing is square to the ram of the press and check that the block and sleeve
assembly is square in the housing pocket.
5. Insert block and sleeve assemblies into the housing pockets.
6. After assembly check the squareness of the sleeve relative to the pocket. All sleeve faces
should be in line and parallel to each other.
The couplings can be installed immediately after servicing, using the assembly methods
already outlined.
MAINTENANCE
1. Every 6 months (or planned maintenance)
Carry out visual inspection of rubber blocks checking for signs of fatigue.
NOTE
Providing that good alignment is maintained then the rubber blocks will last for an
indefinite period of time.
On no account should attempts be make to replace individual layrub blocks. If the blocks
fail then they must be replaced as a complete set of block and sleeve assemblies.
TROUBLESHOOTING
VIBRATION.
Check condition of rubbers.
Check alignment.
Check concentricity of companion flanges and engine mounting.
Check holding down bolts on gearbox and engine mounting.

M1429
Sheet 8 of 8 Issue 01
February 2004
NOISE
Check guard rubbing
Check condition of rubbers
RUBBER BLOCK FAILURE
Check alignment
SPARES
Use only Layrub Block and Sleeves available from:
Twiflex Ltd
104 The Green
Twickenham
Middlesex TW2 5AQ
England
Tel: [phone]