Bsi bs au 025 1964 (2000)

BRITISH STANDARD AUTOMOBILE SERIES BS AU 25 1964 Supersedes S M M T Standard No 51 Specification for Towing hook for use between trailers of 5–14 tons gross weight and towing vehicle UDC 629 11 013 5[.]

Sta nd a r dNo.51

U C 6 9.1 0 3.5:6 9.1 0 3.8

This Bri sh Stan ard, ha ing

b en a pro ed b the

Automo ileIn ustry

Stan ardsCommi e an

en oredb the Chairman

oftheEng ine ring Divisional

Cou cil, was published u der

theauthoriy of the General

Cou cil of the Inst uton on

1 Ju e1 6

© BSI 0 -2 0

The folowing BSI reference

relates to the work on this

stan ard:

Commi e reference AUE/

-Am endm ents is ued sinc publ cation

Pag e

This British Stand rd, which is publ shed u der the authority of the

AutomobieIndustry Stand rd s Commit e of the BSI, is b sed upon

d ata-she t SMMT51:19 7 of the Society of Motor Man facturer and

Tra er Ltd The requirements of this stand rd , which relate only to v ehicles

used on the publc hig hway s, are intended to ensure the ma imum deg re of

inter hang ea i ity betwe n commer ial and Gov ernment dep rtment and

Serv ices stand ard s

The material specifications are for the minimum qual ties ac epta le, and do not

exclude the use of other materials prov id ed that these are at least eq ual in q ual ty

so that roa safety is not imp ired

This stand rd should be used in conju ction with BS AU29

1)

The ho k has be n

d esig ned to ac ommod te a drawb r ey e of2in internal diameter and1; in stock,

or3 in internal d iameter and1C in stock

The stand rd a ples to connections to trai er of5–14 tons g ros weig ht

Thespecification for a towing ho k for con ections to traier of5–3 tons g ros

weig ht is g iv en in BS AU27

2)

an for traier of2 –5 tons g ros weig ht in

BSA U24

3)

N T If i is re uired to conv ert the fig ures in this stan ard fom Bri sh u is into metric u is i

is recommen ed that the conv r ion factor an ta les contained in BS3 0, Conver sion factor s a d

ta ble , b used Attenton is drawn to BS2 5 ,Pr ecis conver sion of inch a d metr ic siz es on

en ine r in d r awin s

A British Stand ard d oes not purport to includ e al the neces ary prov isions of a

contract User of British Stand rd s are responsible for their cor ect a plcation

Com pl anc with a British Standard does not ofitself confer im m unity

f om leg al o l g ations

Sum mary of pag es

This document comprises a f ont cov er, an insid e font cov er, p g esi andi ,

p g es1 to3 an a b ck cov er

This stand rd has be n up ated ( se copy rig ht d ate) an ma hav e ha

amendments incorporated This wi l be indicated in the amendment ta le on the

inside f ont cov er

1)

BS AU2 ,“Dr awbar ye a d for ecar r ia e pins for on eton betwen tr aier s of5–35 tons

gr os weig t a d towin vehicle ”

2)

BS AU2 , “Towin ho k for us betwe n tr aier s of5–35 tons gr os weig t a d towin vehicle”

3)

1 Scope

This British Stand rd specifies the b sic

dimensions an q ualty of materials for a towing

ho k and its mou ting , for use in con ections

betwe n a towing v ehicle and a traier of5–14 tons

g ros weig ht

The g ros weig hts refer to g ros la en train weig hts

where more than one traier is drawn

2 Materia ls

The ho k shal be ma e f om a material of q ual ty

not les than BS9 0 En5( N)

Dimensions shal be as shown in Fig ure 1 an

Fig ure 2

NOT The dimensions sp cified are b sed up n a forg ed ho k,

an ha e b en calculated on the b sis of the total yield streng th

b ing qual to two thirds of the g ros weig ht b ing towed I is

neces ary that any other p rts not co ered b this stan ard,

con ectng the coupling to, the towing v hicle shal ha e a

similar streng th

4 Desig n

An eficient safety catch, prefera ly ofthe automatic

or semi automatic ty pe, shal be prov ided as

indicated in Fig ure 1 to prev ent ac id ental

detachment of the drawb r f om the ho k

The ho k shal be so d esig ned that a b r1 in

diameter, when held v ertical y , ma be p s ed

f e ly betwe n the inside faces of the ho k with the

catch held b ck to clear( se Fig ure 1)

The ho k shal be mou ted with four bolts, C in

d iameter, at4in ×4in centres This render it

inter hang ea le in mou ting with certain

Gov ernment dep rtment and Serv ices stand ard

ho ks

Bolts and nuts shal comply with:

i BS10 3, thr ea d ed B SF, cod e symbol R , or

)

i ) BS17 8, thr ea d ed UNF, cod e symbol R

5)

The n ts shal be secured either b pe ning the end

of the bolt or b fit ing a positiv e locking d ev ice such

as a safe locking n t or a slot ed n t and spl t pin

6 Ma rking

The fol owing wording , in clear let eringBin hig h,

raised or impres ed, shal be marked on each towing

ho k:

“TO TOW14 TONS GROS ” on one side, and on

the other side “BS AU25”

2

3

4)

BS1 8 ,“Pr ecision hexa on b ls, s r ews a d n ts”

5)

BS1 6 ,“Unified pr ecision hexa on b ls,s r ews a d n ts UNC a d UNF thr ead -nor ma l s r ie )

A

B

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