Noise Produced by Brakes on Toronto Subway Trains

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Noise Produced by Brakes on Toronto Subway Trains

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NOT

F O R P?;ULICATION

N O I S E PI?< DUCED BY 8i?AE25 ON TOIIOP!TO STJEIJAY TI!:?INS by T,D, N o r t h w o o d P r e p a r e d f o r t h e T o r o n t o T r a n s p o r t a t f or! C o u m i s s j on R e p o r t N o , '4%. o f t h e D i v i s i o n of B u i l d i n g R e s e a r c h 3.t i;a.y,-.-~ O c t o b e r

1954

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PREFACE

A s

a

p a r t o f I t s work w i t h t h e T o r o n t o T r a n s p o r t a t - i o n Corr~1-nfssion o n t h e c o n s t r u c t i o n o f t h e new subway,

t h e D i v i s i o n o f B u i l d i n g R e s e a r c h o f t h e N a t i o n a l R e s e a r c h C o u n c i l h a s b e e n glac? t o a s s f s t w i t h s t u d i e s o f v i b r a t i o n s and s o u n d p r i o r t o a n d f o l l o w i n g t h e s t a r t o f t r a f n o p e r a t i o n s . T h i s b r i e f r e p o r t by D r . T. D. Northwood, I-iead o f t h e B u i l d i n g P k y s i c s S e c t i o n o f DBR, i s a c o n - t r i b u t i o n t o t h e s e s t u d . i e s , O t t a w a O c t o b e r 1 9 5 4 R o b e r t

P.

L e g g e t Direct012

(4)

Noise Produced by Brakes on T o r o n t o

Subr~.:a;ll-?yai~1~

The p r i m a r y p u r p o s e of t h i s r e p o r t i s t o compare two t y p e s of b r a k e s h o e s i n c u r r e n t u s e on t h e T o r o n t o Rapid T r a n s i t s y s t e m , F o r comparison, some e a r l i e r measu.rements on t h e o r i g i n a l B r i t i s h b r a k e s h o e s a r e a l s o i n c l u d e d .

T4easurements were made w i t h a S c o t t Type 410 Sound Level M e t e r , o p e r a t i n p ; on t h e C Network ( f l a t f r e q u e n c y r e s p o n s e ) . A t t h e l e v e l s invblvecL h e r e t h e hunian e a r % a s f l a t frequency- r e s p o n s e a l s o , and t h e d a t a may be i n t e r p r e t e d a s sound pressi.lre l e v e l s ( i n d e c i b e l s ) o r l o u l i d n e s s l e v e l s

( i n p h o n s ) . No inore r e f i n e d measurement seemed w a r r a ~ t e d , i n view of v a r i o u s u n c o n t ; r o l l a b l e f a c t o r s a f f e c t i n g t h e t e s t s .

Two s p e c i a l t r a i n s were s t u d i e d i n d e t a i l , One of t h e s e was f i t t e d w i t h b r a k e s h o e s made of a n a s b e s t o s

c o m p o s i t i o n , and t h e o t h e r w i t h "Diamond-S" c a s t - i r o n shoes. The l a t t e r - i s now s t a n d a r d . equipment on a l l b u t t h e one c o m p o s i t i o n - s h o o t r a i n . Tlie two t r a i n s were o p e r a t e d by T.T.C, i n s p e c t o r s , who were i n s t r u c t e d t o adh.ere t o a

s t a n d a r d b r a k f n g r o u t i n e . T h i s was done a s f a r a s s e r v i c e c o n d i t i c n s p e r m i t t e d ,

Measurements were t a k e n i n s i d e e a c h t r a i n and a l s o on a s t a t i o n p l a t f o r m a s e a c h t r a i n a ~ r i v e d , Measurements

i n s i d e t h e t r a i n s were made w i t h cornnunica'ting door:: and n e a r b y windows c l o s e d . I t was f o u n d t h a t a n o c c a s f o n a l open window beyond a b o u t t e n f e e t d i d n o t s l [ ; n i f i c a n t l y a i ' l ' e c t t h e r e a d i n g s . The r e a d i n g s o b t a i n e d on t h e s p e c i a l Diamond-S t r a i n a g r e e d g e n e r a l l y ' 1 ~ 1 t h t h e r e a d i n g s t a k e n on a b o u t a d o z e n s i m i l a r t r a i n s , and t h e s e a r e a l l i n c l u d e d i n t h e a v e r a s e v a l u e s r e p o r t e d , U n f o r t u n a t e l y t h e one t r a i n w e a r i n g c o m p o s i t i o n s h o e s was a v a i l a b l s f o r o n l y a b o u t two h o u r s , i n c l u d i n g t h e r u s h - h o u r p e r f o d , b u t i t f s b e l i e v e d t h a t t h e b r a k e n o f s e o b s e r v a t i o n s o b t a f n e 6 adequately r e p r e s e n t normal o p e r a t i n g c o n d i t i o ~ s , O b s e r v a t i o n s

--

1, T r a i n e q u i p p e d w i t h c o m p o s i t i o n b r a k e s h o e s ( a ) I n s f de southbound t r a i n ( 1 i f ; h t l y l o a d e d , n c r m a l s p e e d s ) L e v e l a t maximum s p e e d . . . , . . . 9 2 db. G r a d u a l d e c r e a s e i n l ~ v e l a s b r a k e s a p p l i e d . ( b ) I n s i d e n o r t h b o u n d t r a i n ( h e a v i l y l o a d e d , r e d u c e d s p e e d ) Level a t ma;;imun s p e e d

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Comments: There was p r a c t i c a l l y no d . i s c e r n f l s l e b r a k e n o i s e , g e n e r a l l y , c5 _{t h P s t i a a i n ,} _{The n o i s e o b s e r v e d} d u r i n g b r a k i n g on t h a n o r t h b o u n d t r i p was a low-p5tched rumble s u g g e s t i v e of a s l i g h t l y f l a t t e n e d wheel r a t h e r t h a n s i m p l y t rake n o i s e , 2. T r a i n s e quTpped ~ 5 t h

Df

amo~ld-.S s h o e s

(Measurements aFe a v e r a g e f o r a b o u t a dozen t r a f n s , i n c l u d i n g t h e s p e c i a l l y o p s r a t e d t i , a i n , ) ( a ) I n s i d e sout:hboi,md t r a i n s , l i g h t l y l o a d e d L e v e l

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db, I4aximwn l e v e l d u r i n g b p a k i n g ,

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db. ( c ) S t - C l a i r S t a t i o n , m i d d l e of w e s t p l a t f o p n Average .rna:ciin~u:z I c T T : ~ ~

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_{was main1.g a n}_{u i p i}_t_ched_hi.z, s i n g sol.~.nd, w i t h o c c a s i o n a l - s l i z h t . s q u e a l s t h a t ( l i d ~ o a d d s i g n i f ' i c a r ~ : t l ; ~ t t o .the o v e ~ > a l . l - n o i s e l e v e l .

3.

T r a i n s e q u i p p e d w i t h o?ik;innl E r f t i s h b r a k e s h o e s ( A V L ~ T S - ~ : : ~ of ~ ' ~ a d i n p ; ~ t a k e n i n F e b r u a r y a.nd Marc,h,, 2.9514; C o m e ~ l t s : Brake n o l c > e c o n s i s t e d of a h i g h - i n t e n s i t y s q u e a l , ~ e n e z a l l y s u s t a i r v i q i;k~-i~c ~ l g h o u t th e

braking

o p e r ~ t i o n , C o l ~ c l u s f ons

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of t h e o i % i g i n a l sub',.iay tratil:: -~ras ;;he

squea:Ling bralres. 30th l:i:imlorio-?, and co;nposri:tion brflkc: shoe:::

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e yu_i.pment, T11c t . r a i n or1 ui-pned t s i t l l coniyqs j..tlox. s h o e s b i a s

s i g n i i ' i c a f i t l y quletc.; !; hhan t h o s e ;i\~earin,c; I j l . ~ ~ l ~ ~ i l r ' - . S ~ii:!cje:: 3

producr':ng l i t t l e b r a k e -r,c:.:l.-: c f ailg ki.nd,

2 , I t was obs2r1v-ed. t h a - l tile .;;,.:;.i., f ' : i t t e d u i t h . r;omposf ~ j . o n s.tl0-o~ w a s s l i g h t l y quiet(-;I>, .:ICI- v e r e l g d l ~ r i n q '<?rokfnp, belt i-unr3er.

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