1、BRITISH STANDARD BS ISO 7425-2:1989 Hydraulic fluid power Housings for elastomer-energized, plastic-faced seals Dimensions and tolerances Part 2: Rod seal housings ICS 23.100.99 BS ISO 7425-2:1989 This British Standard, having been prepared under the direction of the Engineering Sector Policy and St
2、rategy Committee, was published under the authority of the Standards Policy and Strategy Committee on 28 August 2002 BSI 28 August 2002 ISBN 0 580 40300 9 National foreword This British Standard reproduces verbatim ISO 7425-2:1989 and implements it as the UK national standard. Together with BS ISO 7
3、425-1:1988 it supersedes BS 6984:1988 which is with drawn. The UK participation in its preparation was entrusted to Technical Committee MCE/11, Fluid seals and housings, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary
4、. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of Britis
5、h Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; presen
6、t to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an in
7、side front cover, the ISO title page, pages ii and iii, a blank page, pages 1 to 3, the National Annex page, an inside back cover and a back cover The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments
8、INTERNATIONAL STANDARD ISO 7425-2 First edition 1989-12-01 Hydraulic fluid power - Housings for elastomer-energized, plastic-faced Seals - Dimensions and tolerantes - Part 2 : Rod seal housings Transmissions h ydrauliques - L ogemen ts pour join ts en des mati however, consultation with the manufact
9、urer is recommended when making the appropriate selection. 6 Dimensions and tolerantes Seal housing dimensions and tolerantes shall be selected from table 2. 7 Extrusion gap 7.1 The extrusion gap is determined by the differente be- tween diameters d4 and d and by any lack of coaxiality of the housin
10、g components. NOTE - Maximum value is achieved when the Piston rod is in contact with one side of the bearing. 7.2 lt is recommended that details concerning the extrusion gap and need for any anti-extrusion devices be the subject of consultation between the housing designer and seal manufac- turer.
11、8 Surface roughness The requirements for the surface roughness of the components in contact with the seal are dependent on the application and Pressu re its life requirement and should be subject to agreement be- tween manufacturer and User. 9 Lead-in chamfer 9.1 To protect the seal from darnage dur
12、ing assembly, lead-in chamfers are required, either as an integral part of the rod end or on a separate assembly tool. 9.2 Reference shall be made to figure 1 for typical location of lead-in chamfer when these are part of the rod end. 9.3 The minimum length of lead-in chamfers, whether on the rod en
13、d or assembly tool, is given in table 1. Table 1 - Lead-in chamfer Dimensions in millimetres Radial depth of seal housing (cross- section), S nom. 2,5 3,75 5,5 7,75 10,5 12,25 Minimum length of chamfer, C 1,5 2 2,5 4 5 6,5 10 Identification Statement (Reference to this part of ISO 7425) Use the foll
14、owing Statement in test reports, catalogues and sales Iiterature when electing to comply with this part of ISO 7425: “Dimensions and tolerantes for hydraulic cylinder rod seal housings selected in accordance with ISO 7425-2, Hydraulic fluid power - Housings for elastomer-energized, plastic-faced Sea
15、ls - Dimensions and tolerantes - Part 2: Rod Seal housings. ” See 5.1.2 Burr-free *) See clause 7. Figure 1 - Example of rod seal housing BSISO74252:20022 BSISO74252:1989OSI 25247 : 9891 lE( Table 2 - Dimensions and tolerantes of seal housing Dimensions in millimetres Housing radial depth s Axial le
16、ngth Rod diameter) Groove diameter d D f8*) tol. L + 0,25 0 r max. I 8 I l3 1 I IO I 15 I 2,5 22 l2l 12 3,75 3,2 2,5 22 14 3,75 32 I 16 I 23,5 I I 18 I 253 -1 20 5,5 4,2 3,75 22 5,5 4,2 O,5 Hg*) 3,75 3,2 I 28 I 39 I I 32 I 43 I I 36 I 47 I 5,5 412 51 I 45 I 56 I I 50 I 61 I 6,3 7,75 5,5 4,2 I 70 I 8
17、5,5 1 I 90 I 105,5 I I 100 I 115,5 I 7,75 6,3 110 125,5 125 Mo,5 I 140 I 155,5 I w 03 160 10,5 81 7,75 6,3 180 I 200 I 221 I I 220 l 241 I 10,5 &1 250 271 -0 304,5 320 344,5 380 3W5 r 1) Bore diameters in accordance with ISO 3320. 2) See ISO 286-2. 12,25 3 BSISO74252:20023 BSISO74252:1989 National A
18、nnex NA(informative)Recommendations for surface texture NA.1 Sliding surfaces The surface texture of components which are in sliding contact with the seal should be 0.1 m to 0.4 m Ra and 1.6 m Rz max., when measured in accordance with BS 1134-1 1) . The bearing ratio Rmr should be 50 % to 90 % at a
19、depth of 25 % of Rz , from a reference line of 5 % bearing ratio. NA.2 Static surfaces The surface texture of components which are in static contact with the seal should be 0.4 m to 1.6 m Ra and 6.3 m Rz max., when measured in accordance with BS 1134-1. The bearing ratio Rmr should be 50 % to 90 % a
20、t a depth of 25 % of Rz, from a reference line of 5 % bearing ratio.1)BS 1134-1:1998, Assessment of surface texture Part 1: Methods and instrumentation BSISO74252:2002BSISO74252:1989BS ISO 7425-2:1989 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent n
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