NATIONAL HISTORIC MECHANICAL ENGINEERING LANDMARK
50,000 Ton
Closed Die Forging Press
UNITED STATES AIR FORCE PLANT 47 Operated by Aluminum Co. of America
Forging Division Cleveland, Ohio
THURSDAY, SEPTEMBER 24, 1981
The American Society of Mechanical Engineers
DEDI CATION CEREMONY
50,000 TON CLOSED DIE FORGING PRESS 1981 SEPTEMBER 24
P E S A N O' S R E S T A U R A N T 6:30 p.m. Dinner 7:15 p.m. Welcome
Donald R. Akers, Chairman Cleveland Section, ASME
In troduction of Honored Guests
Leroy S. Harris, Vice President, Region 5
A SM E L an d m a r k P r o g r a m
P r o f. J . J . E r m e n c , Ch a i r m a n N a t i o n a l H i s t o r y & H e r i t a g e C om m i t t e e
Keynote Address
D r . R ob e r t B . Ga i t h e r , P r e s i d e n t ASME
H ist ory of 50,000 Ton Closed Die Forging Press
Ralph H. Heller, Engineerin g Manager Alcoa Forging Division
ALCOA PLANT 8:00-8:15 p.m. Travel to A l c o a P l a n t , 1 60 0 H a r v a r d A v e . 8:15-9:00 p.m. Plant Tour 9 :0 0 p . m . P r e s e n t a t i o n o f P l a q u e
D r . R ob e r t B . Ga i t h e r , P r e s i d e n t ASME
Acceptance
C ol . Me l v i n F . B r o w n , C om m a n d i n g O ff i c e r DCASR - Cleveland
Final Remarks & Closing
C l yd e R . Gi l l e s p i e , G e n e r a l M a n a g e r A l c o a F o r g i n g D i v i s i on
ACKNOWLEDGMENTS
The Cleveland Section of the American Society of Mechanical Engineers acknowledge the efforts of those members who o r g a n i z e d t h e d e d i c a t i o n o f t h e 5 0 ,0 00 to n C l o se d D i e F o r g e P r e s s p r o gr a m . T h e C l e ve l a n d S e c t i o n a l s o r e c o gn i z e s t h e e f fo r t s a n d c o op e r a t i o n o f p e r s o n n e l f r o m W r i gh t -P a t t e r s o n A i r F o r c e B a s e and Aluminum Company of America.
The American Society of Mechanical Engineers:
Dr. Rober t B. Gaither Leroy S. Har ris Robert A. Woodward Dr. Bur ke E. Nelson
President, Region 5 V i c e P r e s i d e n t , R e gi o n 5 Chairman, ASME Region 5 History & He ritage Committee E x e c u t i v e D i r e c t o r , R e g io n 5
The ASME National History and Heritage Committee:
Prof. J. J. Ermenc Dr. R. Carson Dalzell P r o f. R . S . H a r t e n b e r g Dr. J. Pau l Hartma n Robert M. Vogel Carron Garvin-Donohue
Chairman Secretary
The ASME Cleveland Section: Donald R. Akers James E. Driver Neal Slagter Robert F. Wagner Larry Grabwell Art Nenadal D. K. Wrigh t R. H. Heller
Chairman Vice Chairman Secretary Treasurer Program Chairman Vice Chairman, Public Affairs Chairman, History & Heritage Committee Engineering Manager, Alcoa Forging Division
T h e 5 0,0 00 T on C l o se d D i e F o r g i n g P r e s s i s t h e 6 4t h l a n d m a r k d e s i gn a t e d b y the Society. For a complete listing of landmarks, please contact the Public Information Dept., ASME, 345 East 47th Street, New York, N. Y. 10017.
5 0,0 00 T O N C L OS E D D I E F O R G I N G P R E S S
T h e M e s t a 5 0,0 00 t o n h y d r a u l i c c l o s e d d i e f o r g i n g p r e s s , t h i s c o u n t r y ’s l a r ge s t fo r g i n g m a c h i n e , i s c u r r e n t l y p r o d u c i n g t h e l a r g e s t l i gh t m e t a l forgings in the world. T h i s m a s s i ve f o r g in g t o ol a c t u a l l y h a d i t s ge n e s i s d u r i n g t h e d a ys o f Wo r l d W a r I I . A l l ie d i n t e l l i ge n c e t e a m s i n s p e c t i n g Ge r m a n a i r c r a ft d o w n e d b e h i n d o u r l i n e s d i s c o ve r e d t h a t t h e y co n t a i n e d e x t r e m e l y l a r g e and complex major structural elements. Our appraisal of the situation, c o n fi r m e d i m m e d i a t e l y a f te r t h e e n d o f t h e w a r , w a s t h a t t h e G e r m a n s h a d p r o d u c e d t h e s e a i r c r a ft c om p o n e n t s w i th t h e a i d o f h u ge f or g in g a n d e x t r u s i o n p r e s s e s p o s s e s s in g c a p a b i l i t i e s fa r i n e x c e s s of th o s e i n our own industrial complex. The implications were far-reaching. If forgings and extrusions large e n o u gh t o c om p r i s e k e y a i r c r a f t st r u c t u r a l e l e m e n t s c o u l d b e p r o d u c e d i n t h i s c o u n t r y , n o t o n l y w ou l d f a b r i c a t io n t i m e b e r e d u c e d gr e a t l y, b u t c o s ts w ou l d b e l o w e r e d . In a d d i t i on , s u c h a t e c h n i q u e h e l d t h e p r o m i s e o f f or g i n g m a t e r i a l s w i t h gr e a t e r s t r e n g t h -w e i g h t r a t i o s , a n e x t r e m e l y d e s i r a b l e a t t r i b u t e f r o m t h e s t a n d p o i n t o f a i r c r a f t d e s i gn .
J u s t b e f o r e t h e c o n c l u s i on o f t h e w a r , th e U n i t e d S t a t e s e m b a r k e d u p o n a n u r g e n t p r o gr a m t o b u i l d a p r e s s a b l e t o m a t c h o u r e s t i m a t e s o f t h e p r o d u c t ive c a p a b i l it y of t h e G e r m a n e q u i p m e n t . Th e Me s t a M a c h i n e C om p a n y o f P i t t s b u r gh w a s a w a r d e d a c o n t r a c t t o co n s t r u c t a n 1 8,00 0 t o n f o r gi n g p r e s s , a n d t h e W ym a n G o r d o n Co m p a n y o f N o r t h G r a f t o n , Massachusetts, was selected to operate it. Since the press was so e n o r m o u s , a p a t t e r n t o b e f o ll o we d w h e n t h e p r e s s p r o g r a m w e n t i n t o fu l l s w in g w a s e s t a b l i sh e d — a p l a n t h a d t o b e b u i l t a r o u n d t h e p r e s s t o h o u s e b o t h i t a n d i t s s u p p o r t i n g e q u i p m e n t . T h e w a r e n d e d , h o we v e r , b e f o r e t h e p r o j e c t w a s fu l l y c o m p l e t e d . When our technical/industrial teams visited Germany after the cessation of hostilities, they found that the Germans had indeed d e v e l o p e d a n d l e a r n e d s u c c e s s fu l l y t o op e r a t e p r e s s e s r a n g in g u p t o 30,000 metric tons. In all, three heavy die forging presses, two with a c a p a c i t y o f 15 ,0 00 m e t r i c t o n s a n d o n e w i t h a 3 0,0 00 -t o n c a p a c i t y , w e r e discovered in more or less useable condition. Three extrusion pre sses in the 5,000 metric ton category were also located. As part of the postwar settlement, the United States acquired the 15,000 and 5,000 metr ic ton presses which were channeled into the Air Force Heavy Press P r o gr a m . T h e 3 0,000 -t o n p r e s s , h o w e v e r , w a s s e i z e d b y t h e R u s s i a n s . With the Soviets in possession of so large a press, our Heavy Press Program received added impetus.
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T h e H e a v y P r e s s P r o gr a m Ge t s U n d e r w a y T h e H e a vy P r e s s P r o gr a m a c t u a l l y go t u n d e r w a y i n 1950. T h i s m a r k e d t h e c u l m i n a t i on o f m a n y m o n t h s o f w o r k b y t op p l a n n e r s , i n g ove r n m e n t and industry, who had conducted extensive industrial surveys in an effort to shape a successful Heavy Press Program. At the heart of these studies was the belief that heavy presses could make vital contributions to the defense effort by producing a capability for the production of large structural members for advanced aircraft and other s ys t e m s a t a n u n p a r a l l e l e d r a t e , a t l ow c o st , a n d w i th a h i gh s t r e n gt h w e i g h t r a t i o . Co n g r e s s w a s i n f or m e d o f t h e p r o gr a m , a n d t h e r e q u i s i t e approvals and funds were obtained.
The Concept of the Heavy Press Program T h e H e a v y P r e s s P r o gr a m w a s u n i q u e . To s u p p l y d e f e n s e c o n t r a c t o r s , particularly those in the airframe industry, it was necessary to estab lish a heavy press capability for the production of larger forgings and e x t r u s i o n s w i th g r e a t e r d e f i n i ti o n t h a n w a s a v a i l a b l e i n t h i s c o u n t r y. While the Defense Department policy was then, as now, that contractors, provide their own plant, facilities, and equipment, an e x c e p t i o n i s w a r r a n t e d i n t h e c a s e o f s p e c i a l fa c i l it i e s to p r o d u c e g o o d s fo r w h i c h t h e r e i s n o c o m m e r c i a l m a r k e t . S i n c e t h e r e w a s n o commercial requirement for presses of this size, the government undertook the sponsorship and support of the Heavy Press Program . I t w a s d e s i r a b l e t o e s t a b l i s h a s e l f-s u s t a i n i n g in d u s t r i a l b a s e fo r t h e s e heavy presses. To achieve this objective, industry had to be educated a n d e n c o u r a ge d t o d e s i gn p r o d u c t s su i t a b l e f o r t h e s p e c i a l p r o d u c t i ve capabilities of the presses and to be assured of their continued a v a i l a b i l i t y on a n e c o n o m i c b a s i s . I t w a s e s s e n t i a l , t h e r e f or e , t o h a v e a s u ffi c ie n t n u m b e r o f q u a l i fi e d h e a v y p r e s s o p e r a t o r s i n t h e p r o g r a m s o t h a t w e c o u l d p r o v id e a c o m p e t i ti ve c l i m a t e u p o n w h i c h i n d u s t r y co u l d rely for quality, price, and product availability. The heavy press i n d u s t r y wa s a t f ir s t h e s i t a n t t o e n t e r t h e p r o g r a m s i n c e t h e r e w a s n o a s s u r a n c e t h a t i t w ou l d b e p r o f it a b l e a s a s o u r c e o f e i t h e r d e f e n s e o r c o m m e r c i a l b u s i n e s s . Mo r e o ve r , t h e go ve r n m e n t ’s p r o gr a m , wh i c h w a s predicated on a “strictly business” rental arrangement with the contractor assuming normal overhead and maintenance costs, could, in fact, entail a financial risk. A representative, select group of o p e r a t o r s , h o w e v e r , w a s f in a l l y p e r s u a d e d t o p a r t i ci p a t e . Some Facts and Figures Air Force Plant 47 was authorized to be constructed in 1952 at Cl e v e l a n d , O h i o a d j a c e n t t o t h e A l u m i n u m C o m p a n y of A m e r i c a p l a n t . T h e 50,0 00 to n M e s t a p r e s s i s t h e l a r g e r o f tw o h e a v y p r e s s e s i n s t a l l e d i n t h i s fa c i l i t y. A l c o a h a s b e e n t h e p r i m e o p e r a t i n g c o n t r a c t o r fo r A i r F o r c e P l a n t 4 7 s in c e i t b e g a n o p e r a t i o n o n M a y 5 , 1 95 5. T h e o p e r a t i o n o f t h i s h e a vy p r e s s f a c i l i ty a n d i n p a r t i c u l a r t h e 5 0,000 t o n Me s t a f or g e p r e s s h a s b e e n a k e y e l e m e n t i n A m e r i c a ’s d o m i n a n t role in commercial aircraft. This heavy press facility has supported the aerospace industries since its conception and aided them in their development of advanced military aircraft and aerospace programs and h a s b e e n a p r i m a r y e l e m e n t i n t h e t e c h n o l o gi c a l le a d w e e n j o y i n t h e s e fields.
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T h e M e s t a 5 0,0 00 T o n H y d r a u l i c C lo s e d D i e F o r g i n g P r e s s The Mesta 50,000 ton “Super-Giant” forging press is 87 feet high, extending 36 feet below ground level and 51 feet above. (Figure 1.) The total weight of the press is approximately 8,000 tons. That's enough steel to lay 42 miles of modern railroad track. Sixteen huge steel castings poured in the Mesta foundries at West Homestead, P e n n s y l va n i a c o m p r i s e t h e m a j o r e l e m e n t s o f t h e p r e s s . Ove r 350 t o n s of steel were required to pour some of the largest castings; that is enough steel to supply the needs for 200 passenger cars. There were eight other castings weighing between 215 to 240 tons each. Equipment u s e d t o m a c h i n e t h e p r e s s s e c ti o n s in c l u d e d a M e s t a 18 in c h h o r i zo n t a l b o r i n g a n d m i l li n g m a c h i n e d e s i gn e d a n d b u i l t e s p e c i a l l y fo r t h e j o b . (F i g u r e 2 .) Coming up from the subterranean foundation, two cast steel “stools” c a r r y t h e p r e s s p r o p e r . Mo u n t e d o n t h e s e a r e t w o l ow e r b a s e a n d t w o u p p e r b a s e s e c t i o n s , (F i gu r e 2 ), w e i g h i n g m o r e t h a n 800 t on s , or a b o u t as much as 10,000 men. The movable die table or platen that holds the lower forging die, is a t t a c h e d t o t h e b a s e s e c t i o n s . T h e d i e t a b l e t h a t i s 12 f e e t w i d e b y 26 feet long is withdrawn only when the forging dies are changed. Forge d parts are removed and ingots inserted between the dies by mobile manipulators. The maximum press stroke is six feet. With a working stroke of one foot, the press is designed to operate at 30 cycles per hour. Above the movable die table are 15 feet of daylight, the opening b e t w e e n t h e j a w s o f t h e m o n s t e r v i se . Th e u p p e r d i e i s c la m p e d t o th e u p p e r p l a t e n w h i c h i s a t t a c h e d t o t h e l o we r m o vi n g c r o ss h e a d . (F i gu r e 3.)
The entire moving crosshead assembly — the upper jaw of the “vise”— consists of eight steel castings totaling almost 1150 tons. (Figure 4.) Above this assembly are the stationary crossheads (Figures 5 & 6) housing the eight main hydraulic pressure cylinders. R u n n i n g t h r o u gh t h e p r e s s fr o m t o p t o b o t t om a r e e i g h t m a s s i ve a l l o y s t e e l c o l u m n s m a n u f a c t u r e d a t Me s t a f o r g i n g p l a n t s a t W e s t Homestead, Pa. Forging ingots weighing as much as 270 tons each were p o u r e d b y t e a m i n g t h r e e i m m e n s e l a d l e s o f m o l t e n s t e e l i n t h e fo u n d r y. (Figure 8.) After forging, each column was heat treated in a special f u r n a c e 1 12 fe e t l o n g. T h e f or g e d c o l u m n w a s m o v e d b y r a i l f r o m t h e M e s t a fo r g e s h o p t o t h e i r m a c h i n e s h o p s f o r fi n i s h i n g . So true were the forgings that a perfect finish was obtained by r e m o v in g o n l y on e i n c h o f st o c k o n t h e Me s t a 96 i n c h l a t h e , o n e o f th e w o r l d ’s l a r g e s t . E a c h c o l u m n w a s t r e p a n n e d f u l l l e n g th , to r e m o v e a c o r e 8 in c h e s i n d i a m e t e r t h e fu l l l e n gt h o f t h e c o l u m n . (F i gu r e 9 .) T h e columns were finished to a diameter of 40 inches and a length of 76 fe e t . F o u r s e c t io n s o f e a c h c o lu m n w e r e t h r e a d e d a n d fi t te d w i th f ou r s t e e l n u t s , e a c h 5 2 i n c h e s i n d i a m e t e r . E i gh t o f t h e l a r g e s t n u t s w e i g h 55 tons ea ch!
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The press force is generated by a hydro-pneumatic pressure system consisting of four pre-filler bottles, two horizontal reciprocating pumps driven by 1,500 H.P. motors, and four forged alloy steel pressure accumulator bottles. (Figure 10.) The hydraulic fluid is water with a small amount of soluble oil added to keep the system rust free and lubricated. A p r e s s u r e o f 4,500 p s i is b u i l t u p i n e a c h a c c u m u l a t o r a n d r e l e a s e d t o t h e e i g h t p r e s s u r e c yl i n d e r s h o u s e d i n t h e s t a t i o n a r y c r o ss h e a d s a t t h e top of the press. The combined effort of these cylinders produces 50,000 tons of forging capacity. S u c h f o r gi n g p r e s s u r e s t a g ge r s t h e i m a g in a t i o n ! F i ft y t h o u s a n d t o n s i s equivalent to the pressure that would be exerted by the weight of a s t e e l i n go t 612 fe e t h i g h , p l a c e d o n e n d t o c o ve r t h e e n t i r e 26 fo o t b y 1 2 f o ot d i e b e d . At the end of the press cycle, the hydraulic force is reversed and directed to eight pull-back and balancing cylinders that return the m o v in g c r o s sh e a d a s s e m b l y t o i t s u p p e r p o s i ti o n . The press was rebuilt in 1974 to provide an advanced hydraulic valve system. The resulting control system, now in operation, provides an almost incredible multiplication of the efforts of its operator, as we ll as h a i r l i n e p r e c i si o n . T h e p r e s s , w h i c h s t a n d s e i gh t s t o r i e s t a l l a n d w e i gh s 8,00 0 t o n s , r e s p o n d s i n s t a n t l y a n d p r e c i s e l y t o t h e l o n e o p e r a t o r ’s h a n d o n a l e v e r j u s t t h r e e i n c h e s l o n g . H i s s l i gh t e s t t o u c h g o ve r n s 2 10 0 t o n s o f m o v i n g w e i g h t a n d c a n a p p l y 5 0,0 00 t o n s o f f or g i n g f o r c e . Vital statistics on the system are staggering. There are 23 major c o n t r o l v a l ve s , s om e o f th e m w e i gh i n g a s m u c h a s 1 2 t o n s . F l u i d f l o w s r a n g e f r o m 1 1,7 50 ga l l o n s p e r m i n u t e ( gp m ) h i g h p r e s s u r e t o 2 6 ,4 38 gp m p r e f i l l p r e s s u r e — e n o u g h t o f i ll a g o o d -s i ze d h o u s e t o i t s r a f t e r s i n l e s s t h a n 60 s e c o n d s . E i g h t m a i n c yl i n d e r s -- a l l 6 0 i n c h e s i n d i a m e t e r -- d e l i ve r t h e p r e s s ’s w o r k i n g fo r c e t o a d va n c i n g th e p r e s s p l a t e n . F o u r f i l l in g c h e c k va l v e s , w e i g h i n g a b o u t 12 t o n s e a c h a n d s t a n d i n g n i n e f e e t t a l l , p r e -f il l t h e s e main cylinders to bring the platen quickly into its first contact wit h the w o r k p i e c e . F o u r p u l l b a c k c yl i n d e r s m o ve t h e p l a t e n b a c k t h r o u g h t h e r e t u r n p o r t i o n o f i t s cy cl e . The majority of the control valves are driven and synchronized by a camshaft 30’ long.
Two closed-loop electronic-hydraulic servo systems work simultaneously a s t h e p r e s s o p e r a t e s . O n e o f t h e s e s ys t e m s c o n t r o l s th e p o s i t i o n o f t h e main camshaft, which through positive linkage actuates most of the s ys t e m ’s o p e r a t i n g va l v e s . A s i gn a l i s t r a n s m i t t e d f r o m t h e o p e r a t o r ’s c o n t r o l l e v e r , t h r o u g h t h e e l e c t r o n i c -h y d r a u l i c s e r v o c on t r o l c ir c u i t r y , resulting in positive mechanical positioning of all control valves, e f fe c t i n g a c o r r e s p o n d i n g a n d p r o p o r t i o n a t e s p e e d a n d p o s i ti o n o f t h e p r e s s p l a t e n . Cl o se d -l o op f e e d b a c k c i r c u i t s m a i n t a i n a p r e c i se r e s p o n s e e q u a l t o t h e m o v e m e n t o f t h e o p e r a t o r ’s c o n t r o l l e ve r .
5
I n a d d i t i on t o t h e m a i n d r i ve s y st e m , th e p r e s s h a s a u n i q u e t i lt c o n t r o l system. This was designed to compensate instantly for out-of-level conditions caused during the power stroke by irregularly shaped forgings. The eccentric loads would create high stresses in localized p o r t i o n s of th e p r e s s s t r u c t u r e , w e a k e n i n g it a n d l e a d i n g t o p r e m a t u r e fa i l u r e u n l e s s c o u n t e r a c t e d i m m e d i a t e l y. Th e d i gi t a l a n a l o g l e ve l i n g system uses four encoders to monitor and compare instantly the positions of the moving platen’s four corners. Actual position of the p l a t e n i s s h o wn o n a vi d e o d i s p l a y s cr e e n a t t h e o p e r a t o r ’s s t a t i on . T h e s e s i gn a l s a r e a l s o fe d t h r o u gh a s e r v o m e c h a n i s m t o t w o b a l a n c i n g valves to make necessary corrections automatically by directing high pressure fluid to the proper main cylinders. Conclusion Cr e d i t fo r t h e d e v e l o p m e n t o f t h i s m a m m o t h p r e s s m u s t b e g i ve n n o t o n l y t o t h e b u i l d e r b u t t o t h e U n i t e d S t a t e s A i r F o r c e , i t s Ai r M a t e r i a l Command and, in particular, to its Industrial Resources Division, for their leadership in the development of new manufacturing methods and in the exploration of new ground. They have not hesitated to move a h e a d w h e n m u c h o f i n d u s t r y w a s s a t is fi e d w i t h t h e a v a i la b l e k n o w le d g e a n d k n o w -h o w . T h e y h a v e u r ge d , i m p l o r e d , a n d a l s o p u s h e d ; t h e y h a v e used candy, and sometimes the whip -- but in all cases they were p o i n t i n g t ow a r d s m o r e k n o w l e d g e , b e t t e r k n o w -h o w , n e w m e t h o d s , a n d deeper understanding.
T h e e n gi n e e r i n g e x c e l l e n c e a n d c r e a t i ve i m a g i n a t i on t h a t i s r e p r e s e n t e d i n t h i s m a s s i ve 5 0,0 00 to n c l o s e d d i e fo r g e p r e s s i s a m i l e s t o n e i n m a n ' s a d v a n c e m e n t i n t e c h n o l ogy. From the strong arm and the hammer beating hot metal into durable t o o ls , w e h a v e a d v a n c e d t h e f or g i n g te c h n o l o gy, t h r o u gh t h e u s e o f t h i s c o m p l e x e n g i n e e r i n g c r e a t i o n , t o fo r g e l i gh t m e t a l f or s p a c e c r a f t t h a t w i ll s o on p a s s o u t o f o u r s o l a r s ys t e m a n d w a n d e r t h r o u gh t h e e o n s o f t i m e e x p l o r i n g o u r ga l a x y .
F i gu r e 1
T h e M e s t a 5 0,0 00 t on h y d r a u l i c c l o s e d d i e fo r g i n g p r e s s .
Figure 2
Machining a cast steel ba se section on a Mesta 18 inch h orizontal boring and milling machine.
Figure 3
M il l i n g a n u p p e r b a s e s e c t i o n . O ve r 2 98 to n s o f st e e l w a s p o u r e d in the Mesta foundry to make this casting.
Figure 4
A n u p p e r m o v i n g c r o s s h e a d s e c t i o n c a s t f r o m 6 57 to n s o f st e e l i n the Mesta foundry.
Figure 5 Checking a pressure cylinder port in one of the stationary c r o s sh e a d s w i th a m i c r o m e t e r .
Figure 6 S h i p p i n g a s t a t i o n a r y c r o ss h e a d r e q u i r e d a f l a t c a r w i t h a 2 50 to n capacity.
F i gu r e 7 F i n i s h i n g on e o f th e e i gh t f o r ge d a l l o y s t e e l p r e s s u r e c yl i n d e r s o n a M e s t a 1 10 i n c h t u r n i n g a n d b o r i n g l a t h e . E a c h c y l in d e r w a s m a c h i n e d t o a n i n s i d e d i a m e t e r o f 5 fe e t 1/2 i n c h a n d 1 1 f e e t 7 -1 /2 i n c h .
Figure 8 O n e o f t h e e i g h t a l l o y s t e e l c o l u m n s f o r g e d f r o m a 2 70 t o n i n g ot on a Mesta hydraulic forging press.
Figure 9 T u r n i n g a n d t r e p a n n i n g a 1 0 i n c h d i a m e t e r h o l e t h r o u gh o n e o f t h e p r e s s c o l u m n s o n a Me s t a 9 6 i n c h t u r n i n g a n d b o r i n g la t h e . T h e e i gh t c o l u m n s w e r e f in i s h e d t o 40 i n c h d i a m e t e r b y 76 f e e t long.
F i gu r e 10
T h e h yd r o -p n e u m a t i c p r e s s u r e s ys t e m c o n t a i n s f ou r a c c u m u l a t o r b o t t l e s m a i n t a i n i n g a p r e s s u r e o f 4,500 p o u n d s p e r s q u a r e i n c h . Each pressure bottle was forged in one piece by Mesta from a 195 ton alloy steel ingot.
F i gu r e 11 L o w e r i n g t h e m a s s i ve s t a t i o n a r y c r o s s h e a d s i n t o p o s i t io n o ve r eight pressure cylinders and eight columns.
