BITA GN62

BRITISH INDUSTRIAL TRUCK ASSOCIATION GUIDANCE NOTE MAINTENANCE, INSPECTION AND REPAIR OF FORK ARMS & ATTACHMENTS

GN62 Rev 1 May 2011 Page 1 of 9

IMPORTANT NOTICE PLEASE READ CAREFULLY (a)

The recommendations and advice contained in this Guidance Note are based on specifications, procedures and other information which have been collected by the British Industrial Truck Association Limited (“BITA”) from its members. They represent what is, so far as BITA is aware, the best available data at the time of publication on the construction and use of industrial trucks in the general conditions described, and are intended to provide guidance for such use.

(b)

However, there are a wide variety of situations in which industrial trucks may be used, consequently in all cases the suitability and safety of this Guidance Note must be determined by the person seeking to apply it on the basis of his own judgement, in the light of the conditions in which use is envisaged and subject to all relevant statutory requirements.

(c)

BITA accepts no responsibility for the recommendations, advice, statements, opinions and conclusions expressly or by implication set out below and gives no warranty or representation of assurance in respect of the accuracy or validity of the same.

0.

SCOPE Solid section fork arms and mechanical or hydraulic attachments by their very function are subject to considerable stress. When abused or incorrectly used and improperly maintained, they can suffer decreased service life. Observance of the guidance notes detailed below for maintenance inspections and examination should eliminate failures in fork arms and attachments when working in normal conditions and in accordance with approved operating practices and manufacturers operator’s manual.  

Fork arms are referenced in this guidance from section; 2 Attachments are referenced in this guidance from section; 8

1.

NOMINAL RATED LOAD (WORKING LOAD)

1.1

When fork arms are used in pairs (the normal arrangement), the nominal rated load of each fork arm shall be at least half the manufacturer’s rated capacity of the truck, and at the rated load centre distance shown in Tables 1 to 4, ISO 2328.

1.2

When attachments are used the rating plate on the lift truck should reflect the attachment(s) fitted. The capacity stated should not exceed the capacity on the attachment rating plate.

2.

FORK ARMS

2.1

Maintenance & Inspection Due to their nature there is no maintenance to be carried out on the fork arms other than lubrication of positioning locks.

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BRITISH INDUSTRIAL TRUCK ASSOCIATION GUIDANCE NOTE MAINTENANCE, INSPECTION AND REPAIR OF FORK ARMS & ATTACHMENTS 2.2

GN62 Rev 1 May 2011 Page 2 of 9

The main reason for fork arm wear and damage include incorrect operating practices generally as follows:-.      

2.3

Driving along with forks too low causing contact with the ground Lifting with the tips of the forks causing permanent deformation of the blade. Impact damage resulting in distortion of the forks “Sweeping” or lateral pushing of loads causing deformation of the hangers Insufficient clearance between fork and load, resulting from incorrect fork spacing causing deformation of the hangers Overloading by any means Illustrations of Definitions/Terms

 Top Attachments may be (but not limited to) o ITA Hooks to ISO 2328:2007 o Square Hooks o Tubes for Shaft Mount o Roller Assemblies

 Lower Attachments may be (but not limited to) o ITA Hooks to ISO 2328:2007 o Square Hooks o Terminal West Style Lower Brackets o Roller Assemblies POSITIONING LOCK

TOP ATTACH

SHANK BLADE

BOTTOM ATTACH

TOE

HEEL

TAPER

Fig 1: Fork Arm

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BRITISH INDUSTRIAL TRUCK ASSOCIATION GUIDANCE NOTE MAINTENANCE, INSPECTION AND REPAIR OF FORK ARMS & ATTACHMENTS 3.

May 2011 Page 3 of 9

CLEAN FOR INSPECTION a) b)

4.

GN62 Rev 1

Remove grease and dirt Clean around welds and heel area

EXAMINATION FOR DEFECTS AND MEASUREMENT OF WEAR Competent Persons carrying out examination of fork arms should meet the requirements of BS EN ISO 17020:2004, be capable of detecting defects or weaknesses for the purpose of the examination and have sufficient knowledge and experience to assess the importance of defects or weaknesses and to identify what actions need to be taken in order to rectify them. Particular attention should be paid to:

4.1

Examination for Defects

4.1.1

Identification Marking The rated load and load centre of each fork arm shall be permanently marked on the fork shank, as specified in ISO 2330.

4.1.2

Forks do not necessarily need to be removed from the carriage for examination unless there is doubt about their condition.

4.1.3

Forks are manufactured as a single piece through the fork heel and do not always wear to a consistent pattern so the inspection method should reflect the manufacturing method and wear pattern.

4.1.4

The fork may wear with lateral taper, for example due to incorrect load chain adjustment or load wheel wear/inflation, or longitudinal taper, for example, forks being dragged along the ground with the mast on full back tilt.

4.1.5

Forks with a blade thickness less than the shank are made for specialist operations. In this case the competent person should establish the nominal blade thickness before making a judgement of percentage wear/suitability for continued service.

4.1.6

Visually inspect both top and bottom hooks for deformation which can cause excessive lateral movement and looseness of fit.

4.1.7

Check Positioning Lock Assembly a) b)

Examine positioning lock assembly, ensuring it is in good working order If faulty, the positioning lock assembly should be replaced

4.1.8

The forks should be visually inspected for cracks at the inner heel radius, top and bottom hooks and welded joints. No cracks are permissible, if there is any doubt dye penetrant crack detection media should be used in confirmation.

4.2

Measurement for Wear During manufacture the extreme edges of the fork heel radius may also result in reduced thickness at the heel. If this is the case the point of measurement should be moved slightly forward of the radius.

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BRITISH INDUSTRIAL TRUCK ASSOCIATION GUIDANCE NOTE MAINTENANCE, INSPECTION AND REPAIR OF FORK ARMS & ATTACHMENTS 4.2.1

GN62 Rev 1 May 2011 Page 4 of 9

If any measurement taken exceeds the wear limit of 10% the fork arm should be scrapped. Some forks can be manufactured with a thickened heel, in this case, the comparison between the fork shank and blade heel dimension should still be made. See fig 2.

Some forks are manufactured with extra material here. Wear of this material is not included in the 10% limit.

4.2.2

When examining fork arms the criteria for rejection due to excessive heel wear should be made on the following basis: Fork Thickness Dimensions Nominal Thickness mm 32 35 40 45 50 60 65 70 75 80 90 100 110 120 135 140 150

Minimum Thickness mm 29 32 36 41 45 54 59 63 68 72 81 90 99 108 122 126 135

Note: Fork callipers/gauges may be used to measure fork heel wear. If these devices indicate wear close to the rejection limit the wear shall be confirmed by an accurate measuring device (e.g. an engineer’s rule or vernier gauge).

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BRITISH INDUSTRIAL TRUCK ASSOCIATION GUIDANCE NOTE MAINTENANCE, INSPECTION AND REPAIR OF FORK ARMS & ATTACHMENTS 4.2.3

GN62 Rev 1 May 2011 Page 5 of 9

Differences in fork arm tip height should be measured using the following criteria: 

A set of fork arms shall be checked for any difference in height when mounted on the fork carrier. If the difference in tip heights exceeds 3% of the blade length or that recommended by the manufacturer, the set of fork arms shall be withdrawn from service.

For ease of reference the following fork lengths with a tip height limit deviation of 3% refers:    4.2.4

1000mm length Forks – 3% = 30mm deviation 1200mm length Forks – 3% = 36mm deviation Note: Irrespective of measured deviation, if height difference impedes proper load handling, remove from service.

Forks can be manufactured at different angles between the blade and shank, though 90° is generally the standard. The angle between blade and shank should be checked and the deviation from manufactured angle should not exceed 1°. If over 1° the forks will require resetting by the manufacturer and if over 3° the forks should be scrapped. For ease of reference the deviation from manufactured angle equates to the fork tip height as follows:    

1000mm length Forks – 1 deg = 17mm deviation 1000mm length Forks – 3 deg = 52mm deviation SCRAP 1200mm length Forks – 1 deg = 21mm deviation 1200mm length Forks – 3 deg = 63mm deviation SCRAP

5.

REPAIR, MODIFICATION & TESTING

5.1

Repair a) b)

Fork arms shall only be repaired if the manufacturer or expert of equal competence authorises it. The repair of cracks and the building up of fork heel wear shall not be permitted.

6.

MODIFICATIONS

6.1

Modifications (including welding of brackets, spacers or drilling of holes) other than fork blade shortening should be referred to the manufacturer for authorisation.

7.

TESTING

7.1

After any repair other than that to the fork latch the fork arm should be retested in accordance with ISO 2330 & ISO 5057 and fully certificated before return to service.

8.

ATTACHMENTS

8.1

Attachments are available in a wide variety of designs and capacities to suit specific applications and can vary from simple mechanical units with no moving parts to complex multi-function designs with hydraulic, electrical and electronic components.

8.2

Because of this, these guidelines can only be of a general nature and specific information should always be obtained from the manufacturer’s handbook.

8.3

NOTE: Attachments shall not be used for purposes other than that for which they were designed .

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BRITISH INDUSTRIAL TRUCK ASSOCIATION GUIDANCE NOTE MAINTENANCE, INSPECTION AND REPAIR OF FORK ARMS & ATTACHMENTS

GN62 Rev 1 May 2011 Page 6 of 9

9.

MAINTENANCE

9.1

Clean the attachment before starting work. Particularly around high stress areas, e.g. mountings, bases of carrying rams, clamp arms etc. Try not to wash lubricants from bearings and bushes. Lack of lubrication is one of the main reasons for premature wear of attachment bushes and bearings so ensure that all bushes and bearings are checked for adequate lubrication before returning to service.

9.2

Maintenance will consist mainly of lubricating moving parts and cleaning out accumulations of debris which is often present on equipment used in arduous applications. Increased frequency of cleaning and re-lubrication may be necessary to prevent premature bearing replacement particularly in arduous applications. Ensure that the correct lubricant is used and note that some attachments use a Teflon lubricant applied by spray which should not be mixed with normal grease.

9.3

Adjustment to flow valves may be required to maintain arm synchronisation or correct speed of movement. (Refer to manufacturer’s operating manuals).

10.

EXTRAS

10.1

Many attachments are supplied with extras such as 5th hydraulic kits, camera, multi-stage valves; these also should be checked and maintained correctly.

11.

INSPECTION AND EXAMINATION

11.1

Full operation of all of the attachment functions and a visual check will often highlight an area which might require further attention.

11.2

Check that the attachment rating plate is present and legible.

12.

FASTENERS

12.1

Check the security and tightness of all fasteners paying particular attention to the mountings, arm fixings and rotation bearings. If necessary tighten to the torque recommended by the manufacturer. NOTE! Not all socket fasteners are 12.9 grade which is normal in the UK. Do not replace with stronger fasteners without first checking with the manufacturer.

12.2

Many fasteners are secured with either some kind of applied thread lock or thread lock insert. Some manufacturers recommend replacing fasteners at regular intervals or if the fasteners have been removed. Check the manufacturers hand books for details.

13.

BEARINGS AND BUSHES

13.1

Check for excess wear and clearances in bearings and bushes. Check for play in rotation bearings both around the axis and axially. Excess arm carrier bush wear may negate arm toe in and cause dropped loads. Replace as necessary. On old or heavily used attachments check that the housings or mating surfaces are themselves not worn. Excess wear here may require replacement of major components.

13.2

Note manufacturers hand books for tolerance of arm play, toe in/out, arm alignment.

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5 - 7 High Street, Sunninghill, Berkshire, SL5 9NQ.

BRITISH INDUSTRIAL TRUCK ASSOCIATION GUIDANCE NOTE MAINTENANCE, INSPECTION AND REPAIR OF FORK ARMS & ATTACHMENTS

GN62 Rev 1 May 2011 Page 7 of 9

14.

DAMAGE AND ABUSE

14.1

Look for obvious signs of impact damage, deformation due to overloading or abrasion wear on components due to poor operator practice.

14.2

Be aware that impact damage can transfer to other parts of the attachment.

14.3

Mishandling of loads can also cause damage. Look for signs of mishandling such as paint worn off the inside of arms of Paper Roll clamps, “cuddling” of paper reels can cause internal stresses and failure of welds. Marks on the outside of arms can be caused by loads being pushed. This again may result in undue stresses into the attachment parts and could cause eventual failure or damage.

15.

SACRIFICAL WEAR PARTS

15.1

In some attachment operations it is difficult to avoid parts being rubbed against the ground. To this end sacrificial wear plates may be fitted.

15.2

These may be on the bottom of clamp arms and bodies, or the outside of the short arm of rotating paper roll clamps. Replace before they are fully worn away.

15.3

Fork arms on attachments such as fork clamps and double pallet handlers can also suffer from abuse and wear in the same way as normal fork arms. However, some of these are also fitted with sacrificial wear plates in locations most likely to be affected, e.g. at fork heels. It is acceptable to replace these when worn providing the manufacturer’s instructions are followed. As with normal forks the wear limit of the basic fork blade is 10% and wear strips should not be seen as a way of recovering forks worn to or past this limit. NOTE: with normal forks the original blade thickness can be obtained from the shank thickness but this may not be the case with some attachments. If in doubt consult the manufacturer.

15.4

In all cases use the correct grade of steel or else they will be short lived. Do not add wear pads without the authorisation of the manufacturer.

15.5

Check the condition, i.e. for wear or damage of contact pad surfaces and their security on the base material.

16.

CYLINDERS

16.1

Attachment hydraulic cylinders are used for positioning or clamping the load and should be checked for oil leaks around the cylinder head and inlet/outlet fittings. Also check the cylinder barrel for damage and the base welds for cracks, these should either be repaired by a competent welder or the barrel replaced with new. Check the cylinder rod for wear and more especially indentations or marks which could damage the internal parts of the cylinder and cause leakages.

16.2

Many attachments may have more than one cylinder to perform a function, therefore check correct cylinder stroke lengths and adjust if required.

16.3

Cylinders end fastenings may require setting up to specific torques, also many cylinders require “end float”. In all cases ensure all cylinders are fastened according to the manufacturers instructions (refer to hand book).

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BRITISH INDUSTRIAL TRUCK ASSOCIATION GUIDANCE NOTE MAINTENANCE, INSPECTION AND REPAIR OF FORK ARMS & ATTACHMENTS

GN62 Rev 1 May 2011 Page 8 of 9

17.

HOSES

17.1

Check all hydraulic hoses for oil leaks, security and damage.

17.2

Note: because there is often limited space between the attachment and fork truck it is easy for hoses to become snagged or chafed.

18.

SETUP AND OPERATION

18.1

Check the toe in of clamp arms or tines against the manufacturers’ specification.

18.2

Check the correct operation of the clamp pressure relief valve and the correct operation of the clamp check valve. The best way to do this is using a clamp test cylinder used in a safe manner according to the manufacturer’s recommendations.

18.3

Check security and operation of return or positioning spring and stops, e.g. pad positioning springs.

18.4

Check correct operation of gas struts.

18.5

Operate all the attachment functions to check for full and smooth movement. Note that some rotating attachments that have restricted movement, i.e. are not continuous 360 degrees in both directions, will have some form of stop and or slow down valve cushioning device, check that this is functional.

18.6

Check for synchronisation of arm movement.

18.7

Adjust flow valves where necessary to correct arm synchronisation or to restrict operational speed. Refer to manufacturer’s operating manuals.

18.8

Check for correct operation and adjustment of any switches or sensors which might be used to control part of an operation sequence or provide indication means to the operator.

18.9

Where electrical valves are employed to split hydraulic functions ensure that they work correctly and consistently.

19.

CRACKS

19.1

Check for cracks at highly stressed areas and in particular at the base of carrying rams, carriage mountings, and clamp arm attachment points. If in doubt use a dye penetrant test in the first instance. Magnetic particle inspection should only be carried out by trained and experienced operators.

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5 - 7 High Street, Sunninghill, Berkshire, SL5 9NQ.

BRITISH INDUSTRIAL TRUCK ASSOCIATION GUIDANCE NOTE MAINTENANCE, INSPECTION AND REPAIR OF FORK ARMS & ATTACHMENTS

GN62 Rev 1 May 2011 Page 9 of 9

20.

REPAIR AND MODIFICATION

20.1

Attachments should not be modified without the permission of the manufacturer. Even the shortening of the forks will render the attachment identification plate inaccurate.

20.2

Repairs should only be carried out using original spares or warranties may be invalidated.

20.3

Re-facing of contact pads may require special preparation and adhesives. manufacturer’s instructions.

20.4

Structural repairs should only be carried out with the advice of the manufacturer or an expert of equal competence.

20.5

If retesting is required this should be carried out with a test load 1.33 times the attachment rated capacity.

Follow the

Bibliography

©

ISO 2330:2002

Fork-Lift Trucks – Fork Arms – Technical Characteristics and Testing

ISO 5057:1993

Industrial Trucks – Inspection and Repair of Fork Arms in Service on Fork Lift Trucks

ISO 2328:2007

Fork Lift Trucks – Hook on Type Fork Arms and Fork Arm Carriages – Mounting Dimensions

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