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Technical Handbook Hydraulic Cylinders - Rebuild

TEREX Germany GmbH & Co. KG

3 664 299.00 en

Editor:

TEREX Germany GmbH & Co. KG Department 910 – Product Support D-44149 Dortmund, Karl-Funke-Str. 36 Phone: Fax:

++49 / 231 / 922-4901 ++49 / 231 / 922-5900

© Copyright by TEREX, Printed in Germany

HYDRAULIC CYLINDERS - REBUILD

1. INTRODUCTION 1.1

General ......................................................................................................3

1.2

Safety.........................................................................................................4

1.3

Spare parts................................................................................................4

2. Bearing eyes 2.1

Two part version.......................................................................................5

2.2

Single part version ...................................................................................5

2.3

Eye with spherical bearing ......................................................................6

3. Piston rod 3.1

3.2

Checking component conditions ............................................................7 3.1.1

Cracking ..........................................................................................................7

3.1.2

Roundness ......................................................................................................7

3.1.3

Chrome plating ................................................................................................8

3.1.4

Surface condition.............................................................................................9

3.1.5

Dampener......................................................................................................13

3.1.6

Thread ...........................................................................................................13

3.1.7

Piston.............................................................................................................13

Build-up welding.....................................................................................14 3.2.1

General..........................................................................................................14

3.2.2

Thread ...........................................................................................................15

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3.2.3

3.3

Page - 2

Piston.............................................................................................................16

Machining................................................................................................18 3.3.1

Thread ...........................................................................................................18

3.3.2

Piston.............................................................................................................20

3.3.3

Barrel .............................................................................................................23

3.3.4

Guide rings and seals....................................................................................23

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1.

Introduction

1.1

General

This section describes the procedures necessary when repairing hydraulic cylinders. The illustrations and descriptions correspond to the current series status. It is possible for some illustrations to show details that differ from a particular machine or component. This, however, is of no consequence to the overall function. In case of doubt, consult the TEREX Mining Service. Any alterations and up-grading introduced into the series will be considered in future re-prints of the Technical handbook (THB)

suitable for rebuilding and must be able to organize and supervise such procedures, as well as arrange for the provision of the necessary spare parts. Qualified and experienced personnel, and a suitably equipped workshop must be available to allow all of the rebuild procedures on the TEREX-O&K cylinders to be carried out in an expert manner. The Technical Handbook Rebuild of TEREX-O&K Hydraulic Cylinders belongs only in the hands of specialists for TEREX-O&K hydraulic cylinders.

Rebuild of TEREX-O&K Hydraulic Cylinders.

The regular and prompt replacement of wear parts keeps even older designs of cylinders in a fully operational condition. The procedures for the replacement of wear parts (e.g. seals & guide rings) are described in the Technical handbock of the individual machine type (section 8.8 ‘Hydraulic Cylinders’). It is, however, often desirable to rebuild such cylinders to “rejuvenate” them to a more modern design status. Such a rejuvenation is then always advisable if any mechanical damage needs to be remedied. The longer service lives of new types of seals and wear parts, and the improved operational characteristics of rejuvenated cylinders quickly make the rebuild procedures pay for themselves. This Technical Handbook (THB) describes possible rebuild procedures for TEREX-O&K hydraulic cylinders. The THB is not a tutorial for “beginners”, but a source of reference for the cylinder specialist. The following conditions must be fulfilled: The reader/user must be acquainted with TEREXO&K hydraulic cylinders in daily practice. The reader/user must be familiar with the topics dealt with in the THB ‘Rebuild of TEREX-O&K Hydraulic Cylinders‘. The reader/user must be in a position to draw up a rebuild program for TEREX-O&K cylinders that are

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1.2

Safety

Close up any open pipes, hoses and housing ports to prevent dirt from getting into the system.

Any person involved in rebuilding cylinders must observe the local rules for safety and environmental protection at all times.

Cleanliness is of prime importance. Use only fibre-free cloths and rags (do NOT use cotton waste). Always tools.

Wear a safety helmet, safety footwear and gloves. Wear closely fitting working clothing when working on the machine. Loose, wide garments may catch on machine parts and result in injury.

Depressurize any systems that are to be opened for servicing or inspection work. Take care when hydraulic oil is hot.

the

recommended

When removing seals and wearing parts, always use suitable tools, e.g. snub-nosed screwdrivers, to prevent damaging the sealing surfaces.

Personnel working on cylinders and its components must have adequate knowledge of the procedures involved. Tools, lifting equipment, rigging tackle, trestles, working platforms and other working aids must be in a safe and reliable condition.

use

1.3

Spare parts

All cylinder components are carefully matched to one another. Long-term trouble-free operation can only be ensured when genuine TEREX spare parts are used. The wear and spare parts necessary for the cylinders are listed in the excavator's spare parts list.

Use suitable containers to catch spilling oil. Secure the piston rod against unintended movement when the hydraulic ports are opened or the cylinder is transported. Use suitable lifting tackle to remove and install piston rods and guide bushings. Always observe the safety regulations applicable to the product when handling oils, greases and other chemical substances.

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2.

Bearing eyes

On our machines 2 bearing eye types are used: • •

Two part version Single part version

2.1

2.2

Single part version

In this design concept the eye is threaded and has an axial cut on one side. The eye is directly screwed onto the rod. The bolts create clamping force between the outer thread of the rod and the inner thread of the eye.

Two-part version

In this design concept a nut is screwed onto the rod i such a way that a defined cap is reached between the nut and the eye. The axial force of the assembly bolts is pulling the eye against the end of the rod.

Fig. 2

Single part version - 640002

• The description of the installation of both eye types is provided in the THB – Vol. 1, chapter 8.8 ‘Hydraulic cylinders’. Fig. 1

Two part version - 640001

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2.3

Eye with spherical bearing

The cut in the outside ring must always be 45° to 90°out of direction of the cylinder force (fig. 3). The position is very important for the lifetime of a spherical bearing. To inspect the “ Flange”, yoke or rod end, please use pages 2, 3, 4, 5 & 6 of the Cylinder Inspection Report (appendix 1).

Fig. 3

Page - 6

Position of cut - 640003

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3.

Piston rods

3.1.2

Roundness

3.1

Component condition

Place the piston rod in rollers with the largest possible distance between the rollers (fig. 4):

3.1.1 Cracking

Check roundness with a gauge at following points:

The piston rod must be free of any cracks. To verify this situation, please check with ultra violet black light, magnet particle test or minimum dye-penetrate the area shown on page 15 of the Cylinder Inspection Report (appendix 1).

• • •

The pages 14, 16, 17 & 18 in the Cylinder Inspection Report (appendix 1) are also to be used for the rod inspection.

¼L ½L ¾L

Max. permissible out-of-roundness (gauge reading) is 0.5 mm per 1 000 mm of rod:

Max. out of roundness = If cracks are present at changes in cross section of: • dampener / piston • piston rod / piston • thread / rod or if the dampener or thread has been torn off, rebuilding is not possible and the rod has to be scrapped.

0,5 x L [mm] 1000

Example: For a piston rod with L = 2200 mm the maximum acceptable out-of –roundness is: 0,5 x 2200 1000

= 1,1 mm

If out-of-roundness is greater, place the rod on a lathe or cylinder repair workbench and follow the instruction given on page 14 of the Cylinder Inspection Report (appendix 1).

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Fig. 4

3.1.3

Checking the roundness – 640004

•

Chrome plating

Chrome plating scored, with pitting, dents or arc burns

Foundation layers, e.g. copper or nickel, must not be applied. Copper or nickel foundation layers, or chrome layers of more than the specified thickness can lead to tearing or scale formation and peeling.

Reworking only possible if rod after chrome plating is ground off and scoring, pitting, dents or arc burns must be neither visible nor to be felt and the dimensions are only 0.400 mm less than the nominal dimensions.

Renewal of the chrome plating can only be successful if: •

The old chrome layer is completely ground off.

•

Chrome thickness – min 20 micron, max 200 micron

•

Chrome hardness min. 850 HV 01

•

Base metal surface roughness – R max – 1,6 micron mm

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3.1.4

Surface condition

•

Rough surface with high pressure is high wear on the seals. • A too smooth surface does not lubricate the seals. Chrome surface conditions (fig. 5)

For practical purposes the Rp value or support area tp should always be taken into account! Minimum tp is 60 to 90 %/. Less than 50% is an open profile Fig. 5 is showing 8 examples with the same Rt = 1; but only the examples 5 & 7 show the required figures for tp.

The Rt value alone does not give sufficient information peaks The different roughness profiles have the same Rt. Similarly, the Ra value as shown by the contrasting profiles 6 & 7, which have the same value!

Fig. 5

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Surface condition – 640005

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Fig. 6 shows the profile left by preliminary machining! On the top non cutting process Lower - cutting process

Fig. 6

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Surface condition – 640006

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Fig. 7 shows the measurement of the surface roughness with an electronic device.

Fig. 7

Fig. 8 is indicating the terms for surface roughness. Rt is the vertical distance between the highest and lowest point of the roughness profile over the measured length Im ( on the top). Rmax & Rz is similar to Rt but within the five times shorter measured lengths (center).

Measuring surface roughness - 640007

Ra only gives us an idea of a spot on the surface and is an insufficient measurement. The best results are gained by rolling, drawing, forging and honing with stones and hone oil. Cutting, grinding and honing without stones are the lower quality surfaces.

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Fig. 8

Page - 12

Terms for surface roughness - 640008

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3.1.5

Dampener

3.1.6

Scored dampeners can be reworked without buildup-welding. Smooth off sharp scores (areas 1 & 2, below). Grind on a cone, if no longer present (area 3, fig. 9).

Thread

Threads torn off: Reworking with build-up welding is only possible if the piston rod is made of suitable material. The rod must otherwise be scrapped.

3.1.7

Piston

Stroking surface scored or damaged. Piston to be reworked in order to fit newer type of seal and guide rings. Reworking with build-up welding is only possible if the piston rod is made of suitable material. The piston rod must otherwise be scrapped.

Fig. 9

Dampener – 640009

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3.2

For arc/rod welding:

Build-up welding

3.2.1 General

•

Welding rod DIN 1913: E 5155 B 10 ISO 2560: 515 B 110 29 h

The directions given here have been taken from the

•

AWS/ASME-SFA 5.1: E 7018 BS 639: E 5155 B 110 29 h

Technical Handbook Brand names e.g.: Hoesch Kb 50 Welding for maintenance and repair Part-no 2 114 500.02e. Previous editions of the specifications are no longer valid.

The welding rods have to be dried; – see manufacturers instructions.

Piston rod material:

If build-up welding is needed on thread and piston, do not commence work on the second region until the first region has been welded, fully machined and the whole piston rod allowed to cool down to ambient temperature.

Suitable materials for build-up welding are: • • •

42 MnSI V S 33 CK 45 CK 45 V

The excessive introduction of heat can otherwise damage the chrome plating or affect the hardened zone.

Unsuitable materials are: • • •

Salt water resistant special steel. Piston rods made of this material are marked with X 35 on their ends. 42 CrMo 4 V high tensile 42 CrMo 4 V high tensile and for low temperatures.

Pistons made of unsuitable materials have to be scrapped.

Weld metals: For GMAW: •

Wire electrode DIN 8559: SG 3

•

Filler material: DIN 8559: SG 3 cY 4242 DIN 8559: SG 2 M 2 Y 4664 AVS/ASME-SFA 5.18 : ER 70 S-G Brand names e.g.: Hoesch Weko 4

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3.2.2 Thread Please observe in the following sequence: •

If the thread region does not have a blank journal, tack on a run-out ring (1, fig. 12)

Machine down the thread and the thread runout (fig. 10).

Fig. 12

Fig. 10

Thread run-out – 640 010

•

Check the machined surface for cracks (dyepenetration test). The surface must be completely free of cracks.

•

Grip the piston rod in a rotating clamp. Cover areas not to be welded and especially the chromed areas with non-inflammable covers.

•

Heat up the weld area to 200-250°C.

•

Weld in beads (fig. 11)

Fig. 11

Run-out ring – 640 012

Inter-pass and holding temperature must not exceed 300°C. Deposit sufficient weld metal to enable the welded area to be machined down to the required diameter at all points. Do not (or only briefly) stop work. The component must not be allowed to cool down to below 150°C. When welding is finished, place the component under a non-inflammable cover and allow to cool to room temperature. When the rod has cooled, machine down the weld metal to a smooth surface for cutting the fresh thread. Check the finished weld-metal surface for cracks (dye-penetration). Thread is only to be cut on a surface that is completely free of cracks.

Bead welding – 640 011

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3.2.3 Pistons Proceed in the following way: • Machine down the piston (depending upon the depth of the damage) to at least 2-5 mm under the deepest groove (fig. 13).

•

Also machine down the dampener if it is damaged (area 1, fig. 13)

•

Tack on run-off rings (2, 3, 4, fig. 13).

Fig. 13

Build-up weld on piston - 640013

Grip the piston rod in a rotating clamp. Cover the piston rod with non-inflammable material over a length of at least 500 mm. •

•

Rebuild the dampener with weld beads, but this time parallel to the center line of the rod. Deposit 2 beads, rotate the rod through 180° and deposit a further 2 beads. Turn the rod back again, add a further 2 beads to the first sector, then to the second and so on in this manner.

•

When the required build-up thickness has been reached, pack the piston rod in noninflammable material and allow to cool down slowly to room temperature.

•

When the component has cooled down, check the weld area for cracks (e.g. dye-penetration or magnetic powder test).

Pre-heat the piston to 200 – 250°C.

• Weld in beads. Weld the beads around the piston, starting from the area of the middle groove and then working outwards to both ends. Inter-pass and holding temperature must not exceed 300°C. Interrupt welding if necessary. During breaks, the work piece must not cool lower than 150°C. Long interruptions should therefore be avoided. Deposit sufficient weld metal to enable the welded area to be machined down to the required diameter at all points.

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• •

If no cracks are found the new contour can be machined. After machining is completed again check the component for cracks (e.g. dye-penetration or magnetic powder test).

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3.3

Machining

3.3.1 Thread Machine the threaded end according to table 1 and fig. 14. Required tolerance zone according to ISO 965: 6g

Thread dimensions D1

D2

D3

D4

a

b

e

R

70 80 90 100 110 120 130 140 150 160 170 180 200 220 230 250 280 300

M 65 x 3 M 75 x 3 M 85 x 3 M 95 x 3 M 105 x 3 M 115 x 3 M 120 x 3 M 120 x 3 M 145 x 3 M 155 x 3

58 68 78 88 98 108 113 113 138 148

--------98 108 110 110 125 145

11 11 12 11 15 15 22 22 22 22

95 99 85 104 116 107 145 155 150 150

2 x 45° 2 x 45° 2 x 45° 2 x 45° 2 x 45° 2 x 45° 2 x 45° 2 x 45° 2 x 45° 2 x 45°

16 16 16 16 18 18 20 20 22 25

M 195 x 3 M 215 x 3

188 208

185 185

44 44

190 214

2 x 45° 2 x 45°

40 40

Table 1

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Fig. 14

Hydraulic cylinders - 3664299e.doc- (00) – 03.05 (preliminary)

Dimensions according to table 1 – 640014

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Surface finish and accuracy of shape must correspond to fig. 16.

3.3.2 Piston Details on surface treatment and groove cutting are to be found in figs.15 & 16 and the attached tables. Important Do not alter the length of the piston or dampener.

Fig. 15

Page - 20

Piston Ø 180 mm - 640015

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Fig. 16

Hydraulic cylinders - 3664299e.doc- (00) – 03.05 (preliminary)

Piston Ø 280 mm - 640016

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Explanation of symbols for machining (fig. 16):

Pos. 1:

When rotated around the reference axis AB, the deviation in any measuring plane perpendicular to AB must not exceed 0.02 mm.

Pos. 2: When rotated around the reference axis AB, the out-of-roundness in each measuring plane parallel to AB must not exceed 0.02 mm. Pos. 3: The toleranced end surfaces must lie within 0.02 mm deviation of two parallels perpendicular to the reference axis AB. Pos. 4: The max. roughness on the machined surface must not exceed 6.3 µm (0.0063 mm). Pos. 5: Outer edges with chamfer: Chamfer max. 0.5 mm min. 0.3 mm Inner edges with transition radius R: Radius max. 0.5 mm min. 0.3 mm Roughnesses Rt , Rmax or Rz are measured with electrical apparatus (DIN 4768, part 1, see fig. 7). Pos. 6: The average surface roughness of the machined surface must not exceed 12 µ (0.012 mm).

Dimensions for machining can be found in the matrix (appendix 2).

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3.3.3 Barrel

3.3.4 Guide rings and seals

Scored cylinder barrels can by repaired by honing.

Fig. 17 is showing a barrel with guide rings and seals. Details Y & Z show the position of the support ring. The support ring has to be installed opposite of the high pressure side.

Permissible oversize of re-honed cylinder ( in mm): D max = cylinder dimension + 0.150 mm. Surface condition R max 1.6 if possible by rolling. Check internal dimension of the barrel on the indicated position on page 19 in the Cylinder Inspection Report (appendix 1).

To check the guide please use dye penetration and verify according to dimensions indicated on pages 9, 10, 11 & 12 of the Cylinder Inspection Report (appendix 1).

If any of the dimensions is greater than D max, the rod must be scrapped.

Fig. 17

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Use always genuine TEREX spare parts!

Barrel with guide rings and seals - 640017

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