~ 2~3~S~
1 '~Improve~nt~7 'n Q~ to PneumR~ic Tools"
3 This invention rel~tes to p~eumatic toolsl ~nd more 4 p~rticularly ~ut ~ot exclusively to ~he silencing .5 and/or vibrAtion dampinq of pneumatic to~1s.
~;
7 Pne-~mAtic tool~. are powered by compressed ~as~ th~ gas usually but not nece~Ysarily being air. In thi~
~ spccl~'ication~ referenCeS to ~air~ ~nd to "air t~ols"
are ~o b~ taXen ~unl~s the context prohibits) a~
l1 re~rcn~es r~spectiv~ly to ~se~ in gene~~al and to 12 pneumatic: t~ol~ in general.
1~ , ~eciproc~ting Air ~ool such a~ p~viny ~rea~rs, ls ham~ers~ riv~s!r~ ~ ~nd ~he like convention~lly in~lu~
16 a m~tal cylinder body an~ an air-operated pigton which 1~ reci~r~ t~s witnin tne cylinder body clurinq sustained l~ u.s~ of the tool. ~he ~ylind~ ody h~ ~JI ~h~4L
1CJ ~or ~ ~up of exhaust ports~ through whi~h u~ nir i~
~XhAu~ted durin~ u~e of the tool. Th~ ~i~Loll ~lluLLl~
21 h~ d LvLtl~ withill tl-l~ ~-yli~ n~ it is arranged 22 thAt at or n~r vne end of its trav~l ~ tl~ kiJl~Li~
23 energy o~ th~ pi~tvn i~ ~bruptly tr~nsr~L~d L~ d~l z4 ,~xi~lly mobil~ tool bit, ~vr ~xan~l~ d ~hl~ or ~
` ~ 2 0 '3 ~
1 ~uch rcciprocatin~ ~ir tools ~re notoriously noisy, not 2 lea~t due to the hi~hly impu1siv~ exhausti~l~ ~f u~d ~ ~ir into ~he am~ient environm~nt. Unsurprisillg1y, 4 proposals have been mad~ for ~he silen~ing of S reciproaAtjn~ ~lr tool~, ~enerally in the form o~ a f~ ca~inq cl~mped arourld the. tool body. On~ such cla~p-on 7 c~ilencer c~sing i~ illu~.tr~ted in ~iq 1 of the accompAnyinq dr~win~, and detailed b~low. This known 9 form of ~ilcn~cr is fAbri~ated o~ pl~sti.cs ma~rial, and w~ addinq rela~ively lit~ o th~ qross ~l~iyht 11 of the to~l t ~u~er~ ~rom certain di~adv~nt~gesi the pl~.qti-~s c~in~ i~ le.~ ros~lSt ~h~n the basic tool ~nd 13 is car~ily d~ma~e~ s~y ths rough h~ndling su~,h to~ls 14 frequently r~eive. ~'urther, the plastics material is 5: susceptihle to he.a~ ~amaq~ and deqr~ ion by Ici tcmper~tur~ fluotu~ion~ ~r!d extremes.
l?
1~ A further problem witsl reciprocatinq alr tools i~ their 1~ inher~sl~1y hi~ v~1~ r~f vis~rnti~n, which can lead to o operator t`atique in the ~hort term And to his ~1 physiological dis~unctionaIi~m in the L~nq~r t~r 22 Ag~in, propo~aI~. have heen mad~ for ~ibr~tion 2~ reduction, but the re1evant arrangements tend to be 24 complex and 5u ceptib1e to dsm~qe in nvr~al u~e of th~
tool.
~
27 Moreo~er, ~ilencing arrange~ents and vibration 2~ re~uc,tion ~rrAnq~mentS (where also adopted~ for 2~ r~ciproca~ing air ~ool~ g~nerA}1y require spe~ially 'JC~ ~jhapcd an~ fa~ri~at~d component~, thu~ incurring 3l ~ignifiC~nt ~xtra ~05t~ parti~ul~rly if they ~re to be ~2 m~d~ L~si~;tant to dir~ debri~ ~nd d~m~ge.
34 It is there~ore an object o~ the invention to pravide a )~J p~U~Ati~ r~cipro~Atinq tool havinq a si1encer 2~3~
1 ~rr~ngement which is inherently ~impl~ in fcurm, and ~ whiuh al~o ~orm~ ~ p~otectiv~ h~usi~l~ for an opti~nal ~ vi~ration redu~ti~n arran~em~nt.
~j Accor~in~ t~ the presen~ inv~lltl~n there i provi~
pn~um~tici~ r~iprocating ~ool Gomprisil~ d ~ylincler body nd ~n air-op~r~ted piston whi~h re~ipr~c~L~ within ~ n~id cylinder bo~y during ~stainecl u~,~ u~ ~icl tool, '~ air heing ~xh~usted from an exh~u~t port in sai~
eylin~er body durin~ ~u~h usel ~aid pn~uJ~ tool 11 further compri~ing a silencer ~rrang~mellL ~u~t~nti~lly 1~ totally ~urroundin~ ~aid cylind~r b~yl inc,luding said 1 cxhau~.t port ~hcrein, ~ai~l ~ilencer d~r~n~em~nt 14 oomprii.~ing .~ l~nc~th of metallic ~t~ucLur~ ullow 1~ sectioll Wnose longitudin~l axis is generally parallel l~r Lu the longitu~inal axis of salc~ cylinder ~o~y, and - 17 m~untill~ m~ u~ IlluwlLitl~ ~al~ ~ilencer arrangement 1~ on ~ni~ pneumatic tool.
1 ~
M~tallic .~.~r~c:~ur~l hollo~ section i5 a ~n~nrd 21 ~ngineerinq mat~rial, u~ually of steel~ with ~ ~niLuLm ;2~ cro33-se~:tion which i~i squ~r~ or rect~anyUlaL l:lUt, may ~l alternatively h~ve 50~e o~her ~h~pe such a~ ~ircula~ o~
24 elliptic~l. A~ ~u~h, ~tr~ctural hollo~ ~'Cti~J~ LI
2':, economi~ mnte~i~l in co~parison to ~peci~lly m~ met~l ~G ca3ting~. or ~orc3inc~ while having inher~l~t ~tL~n~th~
~7 i mpAet re.~ Ance ~nd temperature re~i~tallCe.
.
~ ~ 2~
2~ Furthe~r, a pneumatic toal in ~ccor~ance with the ~o i nvention lnd h~ving a 3ilencer arr~ngement comprisiny ~ l a I en~th or met~llic structur~tl hol l~w :7:ie~'tiun 3;7 inh~rcntly provides ~t protectiv~s: CA:::iJ'~l~ r~r ln optional vi brettion reduoin~ ~rrAn~ement linki~ tll~ cyli~ L
dy to th~ rem~in~er of th~ to~l~ ~ucll ~lldL Ll ~5 vibrAtiotl rc:du~ing ~rr~n~ement (when provi~ e~
203~4~
1 ~n~y he designe,~ ~or its vibr~ti~ re~ucing f~nction with~ut Rl~v ha~ing to be inherently resi~t~nt to dir~, d~ris, nn~ imp~
r~ Moreover, ~ pneum~tic tool in ~ccord~nc~ with ~he iS il~Vel~tiCJn ~n~ having ~ 9ilencer Arr~n~ement ~omprisin~
lenyth of ~et~lliC ~truc~ural hollow sec~ion ~ inh~rc:lltly provideY a protective c~ing for the '.3 ~ylind~r body it~.el~ (whether or not the optional lo vibra~ion r~cluc:in~ ~rr~n~ement i~ provi~e~), thu~
,n~blinq ~he ~yl inder ~ody ~d ~ny a~o~i~ted pneumati~
12 ~onduit sy~tem to ~ f~bric~ted of pl~in m~tal tub:ing 13 in contrast to the usu~l ~pecially sh~ped met~1 14 c~stings or ~orgings which are relatively expensive in c~mp~ri.son tc, equival~n~ leng~hs v~ plain tubing.
le. '~'h~refore th~ pre.~en~ inventiOn en~les a pneumatic ~ r~iproo~tinq tool to be fabric~ted of l-~latively 1~ inexpensive st.and~rd engineerin~ materi~ls witll~ut 1'~ compromi~ing the ne~ès~ary robustnes~ Rnd d~mag~
reP,i~.t~n~e of ~u~h t~
~1 .
~2 ';~i~ mounting m~n~; ~or m~untin~ s~id sil~n~et 23 ~rran~ement ~n ~id pneum~ti~ ~ol may comprise ~ p~ir ~4 o~ }Jlate~ utuctll.y :spa~ pc~Lt, dlUn~ L~ rlyi~uc;lin~l ~5 nxis o~ F.~3iC~ l~n~th sf ,structural llu11uw ~e~:tion~ on~
2f~ of '3Aid pl~te~i b~in~ :~ecured to :!iai~ lenqth vf i~7 .~.truotura1 hollow ~;eGtion and the othet- of :~aicl ~l~te~i 20 l:~iny un3ec:ured to 3aid leng~th of :~;tru~tural hollow 2~ ~;cction nncl 1oo~;ely f itt.j n~ th~ere:in whil~ icl~
.10 ~;u~ ntially ri~idly sec~lr~:d t~ -,ai~l oy~ l~L bu~y 31 ~or e~U~ .ta~-itidlly Ligi~ly ~ ;ULt~l~ Lc~ ~ ~;omponent or 3~ c.c~ onc~nts ~hemselves rigidly fie~,ure~ to said cylind~3r 1~ h~ciy), l,ho on~ of s~id plate~ whic.h i~ ;ur ~l I u~4 len~th of stru~:tllral hollow ~;ec~ion beiny e;th~r l y ~ u~ .u sci icl ~:y l l ~ r Llc~y ~ or ric3icl1y ~3~
~ecured to a tool c:Jmp~nen~ or components thems~lves 2 rlqidly :~ec~r~ to sAid c:ylinder body) or ~eing 3 ,~ !,',; i1it3ntly 1ink~c~ through a r~ 7n t vi hrati on 4 r~du~:: i n3 m~n:~ kc~ y l i nder body ~ or r~s i l i ~rltly ~ k~ct throu~3h ~ r~sili~nt vibration red~cing me~ns to :, u tool ~omponent ~ ~om~onentY themsel~es rigi~ly 3cur~d to :s~icl c:ylincler ~o~y ~ . Where one s~d plat~
U is r~iliently linked us afore~aid/ th~ other said piA~ may he rollin<~ly couple~ by ~ rol ler ~y~stem lf~ th~reon t~ the inner ~urface of the ~,aid length of 11 ~itructur~1 hollow c:ec:tion ~uch as to permit mvv~m~l7t of 12 the other ~aid plate ~n~ nf th~ ~ylin~r hody alonrJ t.he 1~ l~ngitudinal axis o~ said length of ~truotu~l hollow 14 section whi le substantially ~eventing rotation of ~aid 1~ oth~r plate and ~f th~ cyli~ r bo~ly ak~out th~:
c3 i Lu~ i r~ xi i ~,r st~ I~nc~t~ f structural hollow 1~ a~ction such that tool-turning force6 ~ppli~ ~y a tool 1~ ~p~LuL~r Lo a L~1 tl~n~ ir~tly ~r indirectly }~ 3ecured to s~id le~th of ~tructural hollt~w s~ction are ~o tr~nC;~it~e~ to c;aid cylin~r body ~n~ ~o a tool bit 2I rotut.ivn~lly ~e~ure~ thereto despite the resiliellt ~2 1 inkiny ~J~ tl~e Olle ~ai~ pl~t~ and Or t~ n~ r 23 3tructural hollow section secured th~rct~ with th~
24 ~ylin~ r bo~y through ~ai--l reoi1i~1lt vi~r~i~n re~ufing 2 t~ mean5 .
~fi 27 Em~odi~en~6 o~ ~he invention will now be ~e~e~~ y z~ w~y of example, with reference to the accompanyl~g ~ drawings wherein:-3n ~1 rig 1 i~ ~tivnal ele~tion o~ a known form of 32 puviny breuker in~luding a plnstic~-ca~ed 33 ~L~ncor:
I'ig 2 i~ an in~omplete 3e~tional el~v~tion of A
rir~ ~m~odimOn~ vE pn~mati~ tool in acc~rdance 2~3 r~
wlt~ ~he invention:
~ Piq 1 i~s n hori~ont~l .sectio~ of the ~irst 3 cm~odi~ent, t~ken on ~he line IrI-III in ~ig 2;
4 ~i~ 4 i~l a ~çhem~tic ~ctional elevation of n ' a.-~on~ ~mbo~im~nt of pneum~tic tool in ac~o~nce i~ wit.h t.hn i rlVe~nt i ~n;
7 ri~ s i~ ~n inçompletc .~e~tional el~v~tion of ~
~ third ~m)~o~iment o~ pneum~tic to~l in ~ccordance r~ W i t~ t~ i nVRIlt ion schematic; seotivn~l ~;ide ~lcv~tion ~ artly in ~ho~t ~utlirl~) of I o~rth ~mbodiment 1~ of pneumutic to~l in accord~nce with ~he 1~ invention;
14 rig 7 i.a. ~ ~sont ~le~ation o~ the Eourth embodiment;
~ 3 u i~ u ~ori ~nt~l section of th~ ~ourth 17 e~ v.~ t, t~ken 0ll ~h~ lin~ VIII--VTTT in Fig ~;;
18 ~ig ~ is another horizontal section of the fourth 1~ embodiment, taken on the line IX-IX in Fig ~:
Fl~ lo ix ~ ~ul~ ic~r~ v~tion of a 21 ~ ~if~ U~'-iilll~ll- ur ~n~ullldLic~ L~ul in accordance ith ~h~ invention;
23 ri~ an lncompl~te asectional ~le~ation of ~4 si~th emhodlment ot pneum~tic t~ol in accordance with th~ inv~ntion; ~nd ri~ 12 l~ ~ a;ch~m~ ~rt-~ectional ~l~vati~n of 2~ n ~ev~nth ~n~i~ent of pneum~ic tool in ~n ~c--o~dallc~, with th~-~ illVlYll~
~9 ~o F~ iin-.~ fiL~. t.u ~ hi~ W'i ~1 ~;e~:tiona1 31 elevati~n of A known ~c~rm o~ pavin~3 breaker tool lO,z which i~: îully .qe~i~rlt~ed ln UK ~at~nt ~peGification Z 0 1 ~ ~ 0 4 ~ 3 i r ~ U~,A ~ u i v ~ .L ~ r t U ~; 4 ~ 2 ~ 0 1 .
3"
~i Th~ ~Javilly ~J~ ~k~:t.- t~JI ~C) ~ alltL~lly ~34~
Gylinder Lw~y 12 wi~hin whi~h ;3 pistc7n 1~ r~ ro~ te~;
in us~ of thc~ tool 10. The pi~ston 14 i~; tlriven by oompre.q~3~cl ~ir d~lmitt~ throu~ n cliL ;IIl~t 1~5 under 4 th~ c:otltr~l o~ ~I rn~nunl ly op~rabl~ Lhr~ttle valve 18 .
~, ~n i~to~c~t ie chun~3e-~ver v~lvc 20 .~c~ li L~; t:~mpressed air r; islto th~ ~yl in~er ~io~ly 12 ~lt~Lrlat:~ly ~t~ov~: the pistc~n '7 14 ~n~i ~through nn ~ir tr~nsfer c;~nduit ;~2~ t:l tl-le ~1 un~ere.id~ Or ~hc~ pistc~rl 14. Thi:~ ~lt-~rlldtf~ air ~:) u~ 3 i on ~ U".t?.'~ thc~ pi.'~tOtl 14 t~ undergo ~I-7u~71~-AI::ti~ 3 lu re~c~ c ~t; on withi n thc cylinder ~dy 1~, u;;ecl Air i ng e~huu~.tce~} i n both dir~tion:~ of pi stc~n mc7tic~r 2 throuc~h ~ crat~tr~l pi~i~c~n-~:ontroll~c~ ~xh~u:-it port ;~
1 :~ fo~me~ i n t.hc: w~ I l ~t t,hf` ~ylirl~leL~ L~ody 1~ .
t th~ low~r ~xtr~mity of its nlovement ~ th~ piston 1 4 lC. I:~)llici~ wi~h u aE>f~ G wl~ ll trun~-.fer.~s th-~ kin~tic 1~ ~nc~qy of thc~ ,~i.iton t~ ~ toc71 bit 28 slidingly 18 rett~inf~cl Ln u ~;hu~;k hou iinc~ 30 ~y ~ tch retain~:r 3~.
I ~
O An i ~lt~c-gt el 1 c~rl~i nc:~ oy I i nf~:r t~nd c 1 t-~ ur~ nd tool , 1 h~3~ld J e 34 i ~ c~ I ~mped tv th~ uppe:r en~ of tl ~ cy I i n~l~r 22 1~ y 1~ t 7 ~;ça l of ~ the cyl i rld~r ~3n~ ;~ ac~ a 21 h~n~lle tC~r m~lni~uluti~?r~ th~ t~c)l 10~ ~hco hHnd)e .')4 c~u n t~ c~ t~1 h~3 n~i l ev~ ~J r; ~ or ~otl t r o l l i t~ h~:
~r, thl-ottle v.-~lve 1~3 thr4ugh ~ pu~h LC~ 38, arld ~; incorpot-~tes nn u~ltomati~ oil~r 40. A ltollow plai~3tic~s '7 ~;j Ir.:ncet .~ ;incj $2 i~s ~lumped arc~und the lower end ot:
2 8 ~ ~ c: y 1 i ~ L I~ 1 Y t 2 ~ i~ A ~; t~ t~ J';t ~ t~ t~ u~i t ~L t .~ 2~ nd t.hu~ rt;~ le ~ me~3sute ot rloi~.e t-e~t-lUCt;On in pc ~ .~ t~ i url t~ h ~ t ~ J W~s Vt? r ~ ~ h ~:~ p ~ a .~; ~ i c, t.'nl,.t~`r' ;.i~'i i rl<j ~ i.'l rlOt t~.~, robust rt~. th~ r te:mRinder o~
~2 ~.~ltt t.V~ 0 ~Lt.~CI~t~ 1Cit1-,:if.)-~ 1 Iy O f t~lti~ik ~lluy !tt : ! ~lrc~,t7 f~r~3ir~3i), l~nd the pl~3~qti~: mnterittl i.s ~l~qo ~4 ~ t ~f.~tih~ r~ ti~tl t~ tt em~?~ tC~it' i~r~A
'rhe followinc~ de~scription detail~ various exemplary embod iment~s Vf p~ring~ br¢ak~r providinq robus~ but ecc~nomi~ ;ilenccr~ wi~h ~hç opt;on~3 of vibration ~t r~:~lucti on nn~ or sub~:ti~ution of ~;uston~-made forqings r~ with plain ~truetur~l hollow se~ion ~nd ~u~ing. rhose 6 pArt5 t~ the f ol lowin~ embodiment~ whi~h ~re the ~am~
7 A~ 01- funr,ti~nc.tlly æquiv~lent to p~rts o~ the ~iq 1 Aviny hre3ker art~ giv~n the sAme r~ferenc~ nu~r~ls;
~J ~c,~ a-lingly fvr ~ full d~:~;cription o~: these pr~rt~
10 ref ~rc:n~e should be meldt- to the ub~v~ t~e~cription of 11 ~ic~ nd ~ i f ne~es~;~ry ~ r~ference should f urther be 1~ m~dc t~ the previously mentione~l UK P~tent 1:3 ~pe~:if ~c~tion ~201~04 ~w2~rein the rere~n~-e nullleral~
14 arc not ~n~i~;tent with those employed in this peaiia~ion).
17 Refert-ing now tc~ Fi~: 2 ~nd ~, these :ihow an l~S Hi r-powc?l-eti pclvin~ L~rei~ke~c 100 o~n~l it;utin~ the Lir~_ 3 ~III~U~ i mt rl~ ~f L21~ ~L~s~llL illV~~ . Tll~ 2~r~dk~L 100 ~0 ~omprl~;e~c~ ~ ~ylinder body 12 ~ormed as a foryinq or ~1 luclull i n~l f ~ 11 h~c~\ry~wall t.U~ ) CI::i t,U l'~dV~ C~ill orc~ inteqrR l upper e~ternnl ~houlder l04~ nn ~:~ inteqt-nl IcJwet ext~rnal ~houlder 106~ and a central 24 exh~u~t ~rt ~4. A one pie~e com~ined pi~ton ~nd ~5 t~pp~t ll~ r~ciproc~tes within th~ bore of the ~-ylil~der ~ JOdY 12 arI~ the tappet portion is yui~-~e~ ~y a bush ll~
27 retain~3 in th~ bore by a ~ir~lip 114.
2~
2~ ~he uE~per enc3 of t~le ~r~ker 100 i~ c:lo~ed off by the 3~ Jt~ uln~inc~ clo~ut~- anc~ t~v1 h~ 34 which 31 ~ r~c3 a~; A v~lve houc3ing tor th~ a~tomatic ~ h~nq~-cve~ v~lve ~.0 and i~. internal:ly por~cd to .~3 pr~vicle r~uisite air pn~sages. ~The manually operatJle 3~I tll~utt1~ ~d1v~ ~1~) which dctuat~-~ th~ ~L~ak~L 100 i~
3~ nc~t -.~hown in Pi~
2 0 3 ~ ~ L~
~3 ~oMp~ 3 ~i r i:~ ~lu~:tc~ rc~m th~ v~1v~ zo to the~
2 ull;ler~ of the p;~.ton~t~ppet II0 ~y A pi.pe llPs whic,h 3 is extern~l t<~ the ~y1incler ~o~ly 1,~. (comE>~lre with Ei~
4 1), nn~l th~ ~ir i:; ~onvcyecl into the lower enc~ of the !~ L~O1-e ~y n ri~lt-AnglC ~ollneGtion 1 ~0 ~;lQntp~d ovcr A
e ~t-L L 1~ in th~ wall of ~h~ cyli~ 2 ~ody 102 ~y mean~ f ~ ~t~ael ~ancl 124 ti~htly cnc:irç1ing ~>oth thc n r onnecto~ o nncl th~s cy1in~er bo~y 102. 'I~his is ~ o ~;hc~wn in ~ i9 ~, wherein t:~e band 124 is clepi~t~ a:;
10 end1~ ut in practice. would probably have a jolnt or ex~mple, a,s in a worm-drive c1ip? . The verticA1 lZ section~1 plan~ of ~i~3 z is an~ularly ~kewed (compnre 1~ wi~h l;~i-3 .J) foI yreater cl~ri~y ~ in~rna1 :~;tructur~al 14 d~tai1.
1'~
lG Enc1Osillg tll~ cylinder body 1Z iq a si1enc~r casing 1Z~
1 r comprisinc~ ~ len~th of ~t!e1 S113 ~ :3tr-lGturA1 llollow 1~ ';ecrtion~, which has ~ qen~r~lly ~qu~re cro~s-:;e~tion 1~ (see ri~ 3). Sui~abl~ dimen~i~ns for the c~sinq 12~;
~0 UL'~ 120 millim~(,r~::; by lZO millim~tr~i with cl welll ;~1 t,hi~;kr~ f ~ il1in~etr~3. Tlle ;~ nc~r cn~ y 12~ i~
m~nted ~n the cylinder body 1~ by ~e~n~ o~ un upper ~ te 12~ ~IJ~ wer p1ate 130~ botl~ L~ 128 d~l~
24 13U fi~in~ wiLhiIl th~ iIl~Lnd1 ~iurl~f Lh~ SHS
f~rming the si1en~er c~ing 12~.
~6 27 Th~ u~r ~ldt~ 128 i~ w~ lt~ periphery to the inner surface of tne silencer casing L~ e upper 3 ~1c~te 1~8 i~ cen~rc~11y ~ecured to the cylinder body lZ
~o ~y beiny ~lamped between the upper extern~1 shoulder ~1 104 nlld ~he ~lo~ine~ en~ ~1Osure~t~1 h~n~1~ 34 33 The lower plate 130 is ~ clearanc~ fit wàthin th~
34 ~r~ u~ 12~ c~ ( ull~ u~y~L~ ylci~ L28 ~ i~
~J n~t pel-ipher~11y ~ttR~hed to th~ ~ilen~r cc~y 12 1 but instead h~ periph~lal cleara~ce 13~ ~r~ Lh~ ir1n~r 2' 3urf~ce of the ~,; l~ncer ça.sing 12~. The lowe~- plat~
~ 0 i~ c-entr~lly seoure~ to the cylin~e~ ~ody 12 ~y 4 bein~ ~lamp~ between the lower extern~l ~hould~r 106 ~n~ the chuck hou6ing :30. An air exh~u~L ven~ 13~ i~
. cut in the lower plate 130, U Irhu~ the upper pl~te 128 se~ures the upper ~nd ~f th~
'~ ~ilencer c~si n~ 12G ~:o the cylinder body 102 ~ whil~ the l~wer plate 130 prevents substantial r~ovement of the 11 lower end of the ~ilencer casin~ 1~6 radially ~u~ Lh~
12 lon~itudinnl axiS o~ the cylinder ~ody 102. Two bolts 1~ (not shown) ~.xt~nd between the handle ~4 and the chuck 14 hou3ing J0 to hold ~he tool components toyether, ~n~
~ o to transmit tool-turning ~orqUe from the handle 34 1~ to the chuck housinq 30.
1~
18 rn use of the tool loO, use~ air i~ ul~lvely discharged 19 through the central exhaust po~-t ~4 has i~ yr~u~
pul~e~ damped withi.n the int~rnAl volume uf th~
21 -~urroundinq silen~er ~ormed by the silen~er ~asing 126 22 ~ L~l~ et~ 128, 1~0. ~he used air i~ tnen rel~tiv~ly smoothly di~harged, wi~h consequent l~w~r 24 noise :lev~ls, throuyh the exh~st vent 184 ~n~ the ~learan~e 13~ to the ~mbi~nt ~nvironment.
While th~ abova-described silencer arrsn~ement has ~he 2~ adv~ntage o ~xtr~.me si~pLi~ity, incre~s~ ef~i~iency ~5 of air pulse da~ping, with ~onse~ue~tly impro~e~
~0 ~ilencing, mhy ~ A~hieved by provicling th~ interiol oL
31 the silencer c~sing 12~ with a pe~meable fillil~q, f~
~ example mlner~l ~ool, and~or with ~uitable baffles 33 which may ~e p~r~o~at~ or iJll~SrUS~L~_ ~ A furth~r ~ign.i~ic~nt ~dvantaqe i~ pr~icl~cl by tho 5ilenoer ~r~;~ngements o~ Fi~s z ~nd ~ in which th~
silenc:er o~ y 126 i~. ~oI-m~d of a length of ~;teel J ~tru~t:ur~l hollow ~;ection. 5u~h m~teri~l ~ which is a 4 st~ndard ~n~.irlee:rill~ m~at~sri~l with consequent economy h o~ prim~ry ~;o~ inhcrently rob~lst and he~nce allt not anly to temperAture ~luctueltioncl but al:;o to impact cl~m~3e ~;uch a:3 might be ca~lc;ecl by the tool 100 l~irl~ drupped or thrown onto ru~bILq~ c;reA~ed by U~3 ~L t~ tool 100. Thtls the ~ilenc~:r c~;ing 126 protects 10 Lhe inte~llal componer~ts of the tool 100 from E:~ch 11 cl~m~y~. This protective :~unc::tion of the ~silencer d~ 2~i ~na~les, f or example., ~he A ir ~ran~f er 13 ~)nduit Ll~ tw be designed ~nd f~bri~;Q~ed with a 14 stren~th suited to its pressure-withs~and duty without 15 ~lso L~Uiriny e~tr~ rol~ustn~ss to with:3t~nd impaat 1~ ~3an r~hus the zlir trnnsf~r conduit: 118 ~nc~ a:Lso the 17 ~ylin~ o~y 12 cnn be formed of ordinary met~l tubing 18 ~dth~L thall the ralntively he~vy An~ exp~n~ive drop 1~ fvrc3in~ vr ~ Fi~ 1 p~ i~L ar~ paviny bre~ker.
AlL~L~ iv~ly the air transfer conduit 118 mAy be ~1 replnced by a length of fle~ible ho~e.
~3 A further Advant~e~ f~ctor in ~he Fig 2 an~ 3 de~ign ~4 ~ um~Liv tool i~ that any dents or distortion~ in L~ n~L ca~ing 126, suGh a~ may be G~use~ ~y 26 illl~d~ ~a~ will h~ve little or ~o effect on the 27 proper ~unctioniny of the tool loo.
~8 ~9 R~f~r~ l'10W to Fiy 4~ thi~ schematic~lly ~epi~s an ~o niL-yvw~e~ paving ~r~uk~r 200 conatit~ting the ~econd 31 ~ o~im~nt o~ the prcsent inven~io~, ~,i~ce many of the 3~ c~m~vrl~n~ v~ tl~e breaker 200 nre conYentional, these 3.3 t~em~J~ L ~ giv~n the reerence numeral~ o~ the same ~ ~r full~Liv~ y ~rts o~ th~ breAker 10 of ~iq 1.
3~
~3~
~rhe c.ylin~e~r body 12 of the breaker ~00 is totalLy enclosed by a ~ nc~r casinq ~0~ ~omprisi~lq a l~ th :3 ot ~teel ~ ,rhich ha~3 a generellly squ~re crose~-sec~ion 4 ~ but which mrAy ~ltern~tively have ~ rec-t~ ul~r or s circ;:ular cro~;s-section). ~he silen~e~r c:a~;ing 20~ i~
6 elo~ed at it~; lower encl by ~ welde<l-c~n plate 204 which f also ~ervee e~; a mountin~ plAte by being clamped b~tween the lower er~d o~ the ~ylinder }:~o~ly 12 ~nd the huck hou2sing 30. ~ r~lbber qasket 20~ is clnJnE~er3 0 between the upper end o~ the ~ilenc~ c~sing 202 and the <~ombined upper end closure/tool handle 34.
1~
1~ ln us~ vf the tool ~oo ~ the pulses o~ used air 14 discharyed ~ro~ the Gylin~er 1~ throu~ the exhaust 1~ port ~.4 are dampefl inside the silencer ~ormed by the 16 cae:ing 20~, the ~nd plAt~ ~04, and th~3 y~k~t 20 17 h~cked ~y the clo:sureth~ndle 34. Th~ u;~ie~ ai~ tlle 1~ r~lativt31 y :3moothly ~n~ rel~tively qui~tly ~ hnrge~
1~ f rom the ~ nc~r throu~h vent~ o~ shown ) .
21 Th~ us~ o~ S~S ~or the silence~ casiny ~02 provid~ the 2Z t,~ul 20U wiLh tll~ a~ s full~;ti~l~l a~ Lru~Lu~1 advantA~es as pr~viou~ly de~ri~ed in re1~tion to the -~4 t~v1 loO Or Fi4~ ~ ~n~ 3. The~e ~van~aqes in~lude the z.5 ~rov~ n ~f ~ ~imple ~nd r~bu~t but e~onomi~ n~er z~ o~sing zo~, ~nd tl~ ability t4 ~a~ric~te th~ c~ d~r 22 body lZ an~ the air trans~er conduit Z2 of pl~in .~ tuhinq.
~9 Referrin~ now to E~i~ S, this ~epicts ~n air-powered 31 ~Vill~ ~L~h~r 3~0 ~OIl~titUtill~ th~ thir~ ~odil~ t 4L
IZ th~ ~r~ent it~vention. The too1 300 i~ g~ner~11y :~J .~imi1ar to the tvvl .100 Or Pi~3 2 u~d ~ and besid~
34 the b~sic paving bre~ker compone~ts previously ~ de~e-i~e~ wi~ll ref~r~llce to Fiq 1~ t~ oo1 3~0 2~3~
.
co~pri~e~ a silencer ~Asin~ ~0~ e~closing the cyiinder ~ bo~y 1~ an~ the ~xhaust port. ~4. ~rhe ~a~ing 302 :~ comprises a len~th Or ~t~l Sl~ having ~ generally 4 squ~re: cro~5-se~ion.
C, The silencer ~asin~ 302 is close~ at: its lower end by a 7 plat~ ~0~ located on th~ lower on~ o~ the ~ing ~2 ~y pin~ ~not shown), or by weld~. Th~ pl~te ~04 is g centrally clamped ~)et~een the lower end of the cylinder body l2 and the c~uck housing :301 ~ut m~y al~ernative1y ~ weld~ ~o the b~dy 12.
13 The upper end of the silencer ~asinq 302 is clo~ed ~y 14 an upper plate 30G lv~ated to the in~ide o~ the c~sinq y ~wl-lw~r~ly ~oj~ting pin~ 308. A sl~ s u~r l~ gask~t 310 is sandwiched be~ween the under-surface of 17 the pl~te 306 and th~ upp~r rim of the casiny ~0~.
~ he ~l~te~ 304 ~n~ 30~ r~ tiv~ly m~unt the lower and -20 upper ends of the sil~ncer ca~ing 302 on the cylinder 21 body 12 to ~orm a mutually secured assem~ly of tool 2X ~omponents.
2~: -24 In use o~ the tool 300~ air ~xhausted from the Gylinder 12 throuqh the exhaust port 24 has its impulses damped 26 within the ~ n~er ~ing 302~ and is ul~imately 27 ~ll~u~ m~ t ~llvir~ L~ U~ r~ r 28 more holes 312 formed in the low~r plat~ 304.
:29 Referring now to Figs 6, 7~ 8 and ~ these depict ~
31 noise-redu~ed ~nd ~ibrAtion-reduced ~ir-powered p~i~q 32 br~aker 400 c~nstitutin~ the ~ou~-th embo~im~llt Or th~
3~ pr~3ent in~ntion ~ ln ~i~ o, t~ nsi~ ~r~a~er mechanism 410 is shown in ~3~
1 Gh~in-dash outline and is e~entially ~imilar to a 2 CO]lV~l~ti~lla.l paving bre~ker m~cha~ism, for example ~s ~ ~hown in ~ig 1. ~'eRtures o~ the break~r ~e~hanism 410 .~ which l~elats ~o ~h~ invention an~/or di~r Yr~m r~ ~onventionul featuro3 are dctail~d below~
7 Th~ tJreak~r ~.ylin~er bo~y 412 is no lo~ger clo~ed ~t its ~ppe~- ~nd by ~ cl~sure eomponent whi~h al~o ~erves ~ as a h~ndle~ but in~stea~ is now upw~rdly ~ontinued ~y 10 columnar ext~nsion piace 414 having a smooth 11 cylincarical exterior surface over th~ major part o its 12 hei~ht~ and a s~rsw-threaded upper end. At a~out its 13 mi~-hei~ht, the e~terior pi~ce 414 has A tr~nsverse 14 pass~g~ ~16 linking its smooth exterior portion to a hollow central b~re 418 leading down ko the autom~tic 16 change-~ve~- valve 20. The pass~e 41~ opens into the 17 hollow interior of a trans~er6e handle 420 such that 1~ the ~rr~n~ement function~ ns a short-r~nge ~lidinq air 1'~ GonneGtibn~ ~or a purpo~e to be dstailed below.
~0 21 Ab~ve tne handl~ ~2~ an~ aroun~ tne extenslon piece 414 ~2 is a resilient rubber ~ush 4Z~ surmounted by a loc~-nut 2 3 4 2 ~ .r~W~ ~n LV L~ lL t~ ~r ~11~ OL Lh~
~4 extensiun ~iec~ 414. ~A ~imilar re~iliently r~str~in~d sliding ~ir conne~tion i~ shown to A l~rger scnle in 2G ~ig 11 ~nd de~cribed below).
2~ The breaker cylinder body 412 is further provided with 2~ a pAir of laterally ext~nding brackets 42~. An upper tr~nsverse ~upport pl~te 43u be~r~ against the 31 underside of the handle 420 and is a clearance fit :J2 around thc cxtensio~ piec~ 414.
34 A pnir ~ ~prin~ e~bl.l~ 432 ~x~end ~tWe~n t~l~
Prackets 42~ and t~e ~upport plate 430. Each spring ` 15 ~ a 1 usse~bly 4~2 c~pri~es ~ coiled compression sprin~ ~34 2 held between the plnte 430 and a spring reL~in~r ~p :~ 43~ by a nu~-and-bolt ~sém~ly 43~, S 5uitahle sprin~ rate~ for th~ ~prings 4~4 are in the r~n~e ~-lO kilo~ra~e~ per inch (1.97-11.8 ki1u~r~m~w~
pe~ centimetre~, The bolt ~f each ~s6embly 43B i~
~liding fit in ~he support plq~e 430 such that th~
~ sprin~ Rssem~lie~ ~2 can con~r~Gt t~ allow ~h~
hr~cket~ 42~ ~n~ hence the cyli~er bo~y 412 Lu nl~V~
1I toward~ the plate 430. ~rhe nut-and-bol~ a~embli~
12 pr~vents unlimit~d e~tension o~ ea~ ~pri~ 34. ~le 1~ lock-nut ~2~ similarly prevents unlimited ~wnwar~
l4 movement of the cylind~r b~dy 41~ rel~tiv~ L~ L}.~
supp~rt plate ~0. During such rela~iYe movement, the lG previously ~e~cribed ~lidiny ~ir ~onn~tio~ weerl Lile 17 h~ndle ~20 And ~he extension piece 414 n~aintdi~
18 ~ontinuous and substantially leak ~ree compressed air 14 s~pply from the interior of the h~ndle 420 to the v~lve 20.
~1 22 Fiy 7 show t}~ oll~w han~le 4~0 provi~ed with the 23 conventionAl air inl~t ~, thruL~l~ v~lv~ (not visible) ~4 ~nd i~s operati~ push-rod 38, an~ the thLuLt1~ uu~l~L~l ~5 lcver ~G, all for ~upplying and contro~ Ll~
~fj oper~ting air for the tool 400.
28 Th~ b~e~ker mechanism 4~0 in~luding the ~re~ker 2~ cylinder ~ody 41Z ~n~ the upper ~upport ~l~L~ 430 i~
~0 ahrou~d by a silence~- casing 440 f~rll~e~ ~y ~ ~uita~le 31 l~ngth of ~quare-~tion SH~. The ca~ing 440 i~
J2 mounted ~n the br~ker 400 ~y bein~ w~l~e~ L~
3~ periphery ~f ~he ~upport pl~te 430 ~e Fi~ n~ 8).
~J5 In order ~o improve the sacurlty of the Illou~lLil~ Lhe ~3~
1 ~llencer ca~inq 4~0 an~ ~o stabilise its ~lignment, the brea~e~ 4~0 ~Ur~ L irl~lude~ a lower kransverse support ~ 442 WhiGh is ~igidly ~,lamped So thc lo~er end o~
4 tne ~reaker me~h~rli~m 410. The nec~ssity of ~llowing tlle u~er sUpport ~l~te 4.30 and the welded-on ca~ing 44~ to move relative to the ~reaker meah~nism 410 for ~f ~t~ proper operation of the resilient rubbcr bush 4~2 and tn~ ~pring a~emblie~ 432 requires ~hat the c~3in~
9 44U ~n m~Ve ver~ lly y~st th~ periphery of the lower 1~ support ~l~te 44~ while ~ein~ ~dequa~ely supported 11 against transver~ mov~ment an~ hence ~gainst ~ce.~.sive 1~ mov~m~nt rd~ially 0~ the lon~i~udinal axl~ o~ thc 13 breaker mechanism 41D. At the same time, since the .L4 han~le 420 i~ clamp~d to the upper support pla~ 430 ~u~ tll~ han~le 4~0 h~ no anqular purch~se on the 1~ exten~ion piec~ 414, t~ol-turning torq~e applied to the n~lle 4Z0 has to ~e tran~nitted from the ~asing 4~0 1~ throu~ Che lower suppvr~ ~lat~ 442 to the breaker 1~ m~chani~m ~lo~
Zl ~l`hese ~i~ul~ ~ou~ require~ent~ o~ the r~la~ive ~Z vérti~l Lreedom co~bin~ with l~teral re~raint ~nd ~orque trans~ io~ ~re m~t by mountin~ A roller 4~4 in ~4 ~ach corner of ~ lu~er ~upp~rt pl~te 4~2 ~e~ ~iq ~), ~a~ tt~e ~ull~L~ 444 being m~un~ed ~nd aligned to run 2G v~rti~lly ~loll~ the inside ~orn~rs o~ the length o~
;~7 ~;~ue~ SHS rol-ming the c~:~;ing 440. (Only one ~uGh ~ roller ls depicte~ ir1 Fi~ 6~ Al~houyh not shown it i3 2~ ~1YU ~llvi~ e~ that the ~llers 444 might be ~V su~titut~ ~y A rolling ball ~rrangemcnt.
'31 32 A y~rL-~ulll~al ~over 44~ caps th~ bre~ker 40V ~3 ~n 3~ upper end clo.sure of t~e ca~ln~ 440 to shield the Upper 34 ~drt~ of the br~er ~ech~nism 41~.
3'~
17 203~
1 1~ operation of the breAker 400~ air exh~usted from the 2 ~ylinder body 412 ~nters the surroundin~ sil~nc~r .3 formed by the ca~inq 4~0, the upper support pl~te 430, 4 a~ th~ lower support pl~te 44z~ The ~tir pui~e6 ar~
damped within ~h~ silencer, an~ nre cli~chlr~0d i relatively ~moothly ~nd with relatively }ittl~ n~
7 (a~ compAr~d to unsil~nced ~isch~rge~ to the a~bient ~nvironment throu~h the clearance betwe~n the ~riph~ry of the lower ~upport pl~te 442 nn~ the enC~mp~sSi.ng 0 ~ilen~r ca~ing ~0 ~se~ Fig ~). Additional Air 1 di~charge ports ~not shown) are optionally forme~ in 2 ~e lu~r ~upyvr~ t~ 4~2 and/or in the sllencer 13 ca~inq ~o.
On the downstroke of the pis~on t not shown in Fi~ ~ but 16 x~e Fi~ 1 ~or det~ils) within the cylinder body 412, 1~ the bre~ker mechanism 410 jerks upw~r~. Th~ brn~kets s 42~ projectillg fr~m ~he Gylin~er ~ody 412 be~r against 19 the he~ds o~ the hol~s in tll~ n~t-~J~ lt a~em~lies 43~ to li~t ~he ~prin~ ret~iner ~ 436 and hence the 21 ~il spl-in~s 434 ~qainst the und~rside ~L ~ up~r 2~ support pl~e 43~. Thi~ r~ili~llt liJIki~ Ule 23 breaker mechani~3m 410 to the upper s~pport plate 430 24 ~n~ h~nc~ ~o ttle t~l handle 4~0 cla~ped to the plate ~30 damp~ the impul~i~e movements o~- the breaker 26 mechanism 410 and thu~ ~educes vibr~ti~n t~nn~mitted to 2~/ the handle 420. The tool op~rRtor Will therefore 28 experience les6 me~nanlcal vi~ra~ion as well as reduce~
2~ acou~tic di~turbance.
31 Th~ rubbsr bus~ 422 da~p~ j~rrin~ on th~ r~uund~ for 32 further reduction o~ vibr~tion~
:~3 84 The previou~.ly de:~cribed sliding ~ir G~nnecti~n be~tw~en the hol~ow han~le 420 ~n~l the ~xten~ioll pi~c~ 414 2~3~
1 ~
l allows the r~l~Live n~Qvem~nt between the brea~er ~ m~chanism 41~ and ~h~ h~ndl~ 4~0 whi~h is necess~ry for : 3 vi~r~iu~ mpinq ~rhile m~intai~ing the flow of 4 ~ompr~R~d air thcrcb~w~n.
T~ rrwJ~ nt o~ ~ig 6-9 thus pro~ide~ ~o~bined noi~e 7 r~u~-iu~l al~ci vibration reduotion in a simple, robu~t, 8 ~n~ ee~rlw~ic a6sembly~ with inherent protection o~ the ~ resilient mountir-~s whi~h th~reore ~o not requir~ to ~e ~siy~ o~ ~bric~ted per ~ in an impact~re~istant ll ~orm.
1~
1~ Fiy~ lo, ll, ~nd 12 illu~tr~te ~hree furt~.r 14 arran~ement~ ~dCh p~oviding noise re~uction combined l~ wit~ vibration reduction and dam~ge re~ rl~. Th~6e 16 three arrangements are each ~enerally similar to the l7 arrangemen~ ~h~wr~ in ~ig 6 and detailed abo~e with 18 r~L~L~ e to ~iys G-9. ~asic similA~ities ari~e in l~ respect o~ the ~il~r~r ~ing b~inq a lenqth of square ~or rectangul~r) ~Iu~tural hollow secti~n mounted on 21 an uppeL support plate around wh.ich it i9 welded, and 'U~ U~L ~u~p~Lt~d by a lower ~upport pl~t~ which i~
23 ~u~ o th~ breaker ~echAnism bu~ ~ns~ured to the 24 ~il~n~r ~asin~. In e~ch case, th~ tool handle i~
: 25 clamped to the u~per ~ide of ~he upper support plA~.
;~6 ln each arrangement, tne brea~er me~hanism has an ~7 upwardly pruje~-irl~ ~xtension pie~e with an int~rn~l ~ air passage sli~.ingly lin~ing tne autvm~ti~ change-over 29 valve tv ~Je holl~ cel-ltre of the t~ol h~ndle to form a :~o sliding connectlon ~or compre~s~d air. Fur~ r, ir 3l each of the ~rr~n~n~ t~ Or Fi~s 10 and ll, th~
32 centrally mounted breaker mech~nism is resiliently 33 linke~ to the a~sem~.ly o~ ~he handle, upp~r support .-14 plate, an~ r~ r ~q~isl~. Th~ resi.lient lin~ form~
35 th~ vibration reductivn m~ns an~ comprises one or more 2~3~4~
1~
l ~oil~ c~mpre~ion ~prin~, tho~gh ~th~r ~orm~. of 2 rrd~iliellt linkaye c~n b~ employed~ which may f~r 3 ~xamp.le be m~talli~ or non-me~allic. lrhe re~ilient 4 lillh irl ~oth ~r7-anqements further comprises an ~nnul~r ru~ r ~ush throuqh which the upper ~end o~ tho G ~x~erlsiull pl~ce holds down the tool h~ndle. [A
7 ~mewllat. ~iLf~rent fo~m of vi~r~tion redu~tion i~
~mp~oyed in the nrran~emen~ ~P Fig 12, and will b~
~ describc~ bc~low).
11 In view o~ ~hese similari~ies to the ~rr~ng~mqnt of l2 Fig~ 6~9 ~n~ tv avoid repotiti~n, ~he following 13 r~tailed ~scrip~ion r~f the ~rran~ement~ of Pigs lo, l4 ll, and 1~ Will concentrate on si~nlflcan~ ~etail dif~eren~e~ Cr~my~lent~ arl~ asse~mb.lies in the 1~ arrangements of Yiqs 10, 11 and 12 wnicn are ~e same l~ as or ~unc~londlly equivalent to components and l~ asse~lies ln the arran~ement of Fir~s ~-~ will ~rd yive l~3 the ~ame re~rence numerals AS wer~ used in Pigs ~5 2~ L~uL wiLn Lh~ ~4~ repl~ced ~espectively b~ ~ '5', a 'G', % l OL d ' ~ nvell~ion~l Gompo~entS ~erived from the ~i~
22 l artan~m~nt ha~e unaltered reference numcrals.
23 Ac~o~di~ y, ~or n det~iled description of any p~rt of ~4 Lll~ dLL~J~ oellts ~f ~igs lO, ll, or 12 not given below, 25 r ~f ~r ~n~ should s.7e made to th~ relevant part of ~he ~6 description of ~ig5 ~-Y.
~8 Specific~lly re~erring now to Fig lo, thie 2g ~h~ ti~ally illu~tr~tes a p~vin~ breaker 500 forming the ~ifth emb~diment of the pres~n~ invention. Tn 31 pl~ of ~t~ s~d~h~t~ 42~ in ~h~ Fiy ~ ~reaker ~oo, the 32 ~ iUII ~ 514 is ~ormed with ~ should~r na~r it~
33 1~W~L ~SI~ tO ~ear against the lower en~ of the coiled 34 ~:O~ r ~S~iOn spring 534. The low~r suppor~ pl~te 542 is ~5 rO.ll~r-rL-~ ~SI~ d ~liding fit withis~ the silencer ~3~
ZO
1 c~in~ 5~0 ~or lat~ral r~tr~int and torsional linkin~
2 of the e~si.nq 540 to the breaker mech~ni~m 510.
4 ~he ~nvin~ bre~k~r 500 functions to p:rovide n~i~e redu~tion ~n~ vibration r~du~tion in ~,he same manner AS
f; the hr~ak~r ~nn of ~ig~ 6 `7 8 Turnin~ n~w to F~ig 1:L, thi~ shows p~rt ~f ~ paving 9 breaker 60Q constitutin~ the si~th embodiment of the lC~ pre~ent invention. The bre~ker 600 i5 largely Il i~erlti~ o ~ br~ak~r 400 tcomp~r~ Fig 11 with Fiq 1~ 4), substantlve ~etail diff~rences lying mainly in an 13 ~symmet1-ical ~rL-~nqement within the bre~ker G00, ~nd in 14 the provi~ion of tiebolts GSO (only one being vi~i~le in Pi~ n~.horing the exten~i~n pi~e 614 to the 16 chuck holder 30.
18 Turniny fin~lly to Fig 12, this shows a p~ing bre~ker lg 700 constituting ~ ~eventh embo~iment of the present 2~ inverlLion. Th~ ~re~er 700 i~ yene~-ally ~imilar to ~he .l breaker 500 shown in Fiq 10~ but dirrers siqni~icantly 22 in re~p~ct of the me~s pro~i~e~ for reducin~
23 vi~ration.
~4 n~y~ ,o 1;;1~ Fig 10 arran~ement I in the b~e~ker ~ 700 the c~bined upper-snd cylin~er ~lo~ure and 27 automatic change-oV~r valve housin~ ~715 in F'i~ 12) is 2~ ~ component whi~h is now di~inct from ~n~ re1atively 2'~ wv~le ~ith L~pect to ~he ~xtension pi~-~ 714. The .30 cyli~der closu.refvalve ~lou~ing 715 l~ ~lidingly ~
31 around the low~r end of the extension pi~e 714. The ~2 closure~housin~ 15 i~ prevont~d ~rom b~in~ pull~d or 33 pushed o~f the low~r end of the e~ten~ion piece 714 by 34 an inteyral shvulder or flAnge 7~0 provided ~hereon.
21 2~3~
L The exten~ion pie~,e 714 it:ir~ al~o in two part~, 2 l~wer tu~ul~r component 7~2 yrovi~inq the air pn~s~ge~
3 /1~ an~ 718, ancl ~n upper~ scr~w-thr~adad ~tud 7~J~
4 which h~ .Its lo~er end ~r~wed into the upper end of th~ tu~ul~r component 762. rrhe n~t ~ 6 ac~ through ~ne wash~r 7Z4 an~ ~he resiliant r~bkler ~ush 7~ to 7 resillently restr,~irl th~ ext~3nsion pi.ece 714 ag~in~t 8 all ~xcept ~ limi~e~ ~ownw~rd movemerlt relative to the r~ nan~le '~. upwar~3 movement of th~ ~x~ension piec~ 714 rela~ive to ths har~ 720 is entirely prevented hy 11 abutment o~ the u~ en~ of the tubular componcnt 762 12 with the portion o~ tne nandle J20 ~UrrVUII~ing ~he bore l3 for the stud ~4.
In considering vibra~ion damping in the breaker 700, it 16 is important to note tn~ the closure~uu~ y 71'J
17 slides on tne relatlVe.ly immobil~ bular component ?G2 18 o~ tne extenslon piec~ 714 i~l th~ ma~n~r of an inverted 19 piston/cyllnder arr~rl4~ lt, with the closure~hou~ing 2~ 715 pl,~ying ~he p,~rt ~f ~he pi~t~n. Thc cro~-~1 sectional area o~ ~ne tubul~ component -762 ~uh~ t~
22 ~rom tne up-racing ~re~ uL th~ "piston" 7~ 5.
~3 24 Thus in operation o~ ~he breaker 700 wlth the intern,l 2~ air pa~saqes between the throt~le valve la and th~,~
'~. change-over valve 20 filled with ~ompressed air, this in~ern~l pnsumatio ~re~surisation of the closure~nousing /15 ,~ ~r~ th~ di~erential "pi~ton~
~ reas ~nerOn tu ~r~vi~e d net d~wnwar~ bias on the :~ closurefhousing 715 ~r~ th~ remAindeL- of the bre~ker .~1 me~n~nism 710 ~t~hed there~o. lrherefor~ ~pwardly 3~ impul~ive movemen~ o~ the bre~k~s m~ rti~m 710 i5 J:3 re~lliently count~r~ted by th~ prt~u~ti~Ally -induce~ ~ownwar~ uce the pn~umati~
equivalent of the mecnaniaal sprlng ~34 present in ~t~
2 ~
1 ~re~k~r 500 o~ Fig 10~ to provide ~ib~at;on reduGtion.
Downward rebound of the bre~ker ~ech~nism 710 i~
~ L~ ntly limit~d ~nd d~mped by ~h~ rubber ~J~h 7Z2 4 ~ctirlq through ~h~ ext~nsion pie~e 71G and the shoulder ~ ~0 wh~n ~h~ ~106ure~hou~inq 715 81 icle~ down the 6 tu~ular cc~mpvnent 7G2 into CO~ w1th ~h~ shoulder 50.
9 'rhe silen~er casln~ 740 is ~ormed o~ n l~n~th of ~tructural hollow section AS in previously described 11 ~m~odim~nts, and provides noi~e reduction in the sAme 12 ~anner.
1~
l4 Thu~ seven exemplAry embodiment~ of the invention h~ve been ~es~ribe~, all providinq noise reductlon and/or 16 vibr~tion r~duction by means which are simple, robust, 17 and economic per se, and which turthermore facilitate 1~ the optional constrUction o~ ~ne air ~ool as a wnole 19 from re~atively low cost mAteri~ls with~ut compromi~in~
essential robus~ne~s an~ d~mag~ resis~nce.
~1 22 While certain modifi~ n~ ~n~3 v~r.i~tion~ ~f ~h~
23 i~vellti~;l h~ve b~n des~ribed ~bove/ the invention i~
~4 not restricted theseto, ~n~ ~t~s ~ ti~n~ ~n~
2~ vibration~ can be ~dopt~d wi~h4ut dep~tinq trom the 2G ~cope o~ the in~e~tion~
~ .
.~2 ~4 ~5