HST ANTI-SPALL WINDSCREENS (0071/070042)

Transcription

1 Unipart Rail Ltd, Jupiter Building, First Point, Balby Carr Bank, Doncaster, South Yorkshire, DN4 5JQ HST ANTI-SPALL WINDSCREENS (0071/070042) 16 March 2012 Safety Related Product Compliance X Obsolescence Reliability Product Development Other Approval and Authorisation Signature Technical Author: Checked by: Approved for use by: Authorised for use by: R Chappell Product Engineer Unipart Rail Ltd M Spreadbury Product Engineer Unipart Rail Ltd G Cartwright Customer Engineering Manager Unipart Rail Ltd N. Tinworth Acting Engineering Director Unipart Rail Ltd This is a proprietary technical publication issued by Unipart Rail Ltd. This technical publication (including any information relating thereto) is not to be used, disseminated, reproduced, copied or adapted, either in whole or in part, without the express written approval of the Engineering Director at the above address. Any comments or technical queries on the contents of this document may be directed to Unipart Rail Ltd tel: engtechsupport@unipartrail.com or at the above address. Copyright Unipart Rail Ltd Issue 2 Revised February 2012

2 Page: 2 of 9 ISSUE/REVISION RECORD Each time this document is amended it will be completely re-issued. Amendments will be indicated by a vertical line in both margins. Iss/Rev Date Page Numbers Revised 1/A March 2012 First Issue Supply Copies of this Technical Bulletin may be obtained from the Customer Support Manager, Unipart Rail Ltd, Jupiter Building, First Point, Balby Carr Bank, Doncaster, South Yorkshire, DN4 5JQ. Tel: or by engtechsupport@unipartrail.com

3 Page: 3 of 9 CONTENTS Section Title Page No. Approval and Authorisation 1 Issue/Revision Record 2 Contents 3 1. Introduction 4 2. Product Identification 5 3. Details 6 4. Actions 7 5. Revision Letter 9

4 Page: 4 of 9 1. INTRODUCTION (catalogue number 071/070042) are manufactured using a layer of polycarbonate bonded to the face of the windscreens glass. Differential expansion rates between the dissimilar layers cause the windscreen to bow, particularly when the windscreen temperature is low. This had led to concerns from customers regarding the allowable degree of bow, and the possibility of damage to the windscreen during the fitting or in the longer term. This Bulletin defines the storage and measurement requirements for, including the maximum allowable bow and at what temperature. It also includes GKN s recommended method for tightening the windscreen fixing bolts to ensure a bowed windscreen is fitted in a controlled manner so as to prevent damage.

5 TECHNICAL BULLETIN 2. Issue: 1 Page: 5 of 9 PRODUCT IDENTIFICATION BR Catalogue Number: 071/ GKN Part Number Product Description: HST Anti-spall Windscreen Applicable Vehicle Type(s): HST (Class 43) Power Cars As supplied Close up showing orientation in crate Photo 1 Photo 2 Showing orientation in crate (anti-spall face downwards) Photo 3 Photo 4

6 Page: 6 of 9 3. DETAILS HST Power Car windscreens (catalogue number 071/070042) are manufactured with an anti-spall layer comprising polycarbonate bonded to the windscreen glass. This is to provide protection for the driver should the windscreen become broken by impact with objects in service. The polycarbonate layer has a greater rate of contraction than the glass such that during the manufacturing process, the cooling of the bonded windscreen causes the polycarbonate layer to pull in the glass structure, causing bowing of the windscreen. Manufacturer GKN Aerospace has experimented with a two-stage autoclave process to control the degree of bow, but it has proven impossible to eliminate. GKN in conjunction with Unipart Rail have undertaken measurement of sample windscreens to determine the degree of bow, and the change in this over a range of temperatures. This has helped determine an acceptable degree of bow, and at what temperature the bow should be measured. GKN have also determined the optimum fastener tightening sequence to be used to fit a bowed windscreen.(see page 8)

7 Page: 7 of 9 4. ACTIONS The following actions are to be taken for the storage, measurement and fitting of an HWT anti-spall windscreen: 4.1 Windscreen Storage & Measurement a) Each anti-spall windscreen shall be stored in the orientation in which it was shipped. b) The windscreen shall be held in the area where the measurement is to take place for a minimum of 8 hours either in an open box, or removed from the box to stabilise the windscreen temperature. c) The bow in the windscreen shall be measured using a calibrated straight edge placed along the long axis of the windscreen. Note: Extreme care must be taken so as not to damage the windscreen during measurement. d) Windscreen bow of up to 14mm at an air temperature of 1 O C or above is acceptable to fit. GKN have confirmed that the integrity of the windscreen will not be affected by fitting in this condition. 4.2 Windscreen Fitting a) All windscreens must be fitted using the bolting sequence contained in GKN drawing QDA 1218 issue 01, a copy of which is supplied with each windscreen. b) The use of longer than standard windscreen fixing bolts to initially pull the windscreen into the cab structure is permitted provided they are then replaced by standard length bolts and the GKN tightening sequence is followed. c) After initial tightening, following the bolting pattern around the windscreen as many times as necessary to ensure the bolts are fully tightened. Further Information This bulletin has been compiled to assist customers to fit bowed windscreens to vehicles following successful trials with GKN Aerospace and the HST user group. If you require any further information or assistance please contact your Unipart Rail Account Manager or Customer Engineer.

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9 Page: 9 of 9 5. REVISION LETTER Content from the previous issue has been deleted, moved and/or modified as detailed in the table below: Section Page Change Reason for Change N/A All First Issue