The Use Of Clevis And Rod Ends In Rocket

The Solid Rocket Booster's are made up of four main segments

. They are joined together by a Tang and Clevis joint. Each segment has a Tang on the bottom and a Clevis at the top. The Clevis has a shape like a "U", while the Tang has a shape of a straight line. The Tang would fit by sliding down the sides of the "U" of the Clevis. The Aft Mid Segment connects to the Aft Segment with the Nozzle. The joint that connects these two segments together is called the Aft Field joint. This is the joint that failed on the Right Solid Rocket Booster. The joint is sealed by two rubber O-rings, with a diameter of 0.280 inches (+ 0.005, -0.003). The sealing is used to stop the gases from inside the SRB escaping. The seal had failed, because the flame seen during the flight was gas being burnt.

Assembly of the SRB could have damaged the sealing joint. The segments of the SRB are transported to the assembly plant horizontally. Each segment is heavy and therefore with its weight, changes the shape of the segment so it is not perfectly round. The irregular shape of the segments can be distorted and stressed from previous missions, and or the effects of handling. At assembly the aft segment is lowed vertically, with the tang sliding into the clevis of the previous joint. Because of the distortions, the dimensions of the segments may have changed. Mission 51-L, was one of the missions where the dimensions had changed. Even during the assembly process of the SRB the dimensions of segments continue to change, with the amount of weight that is applied to each of the segments. As stated, the shape and dimensions change, so at the assembly plant, to make the segments fit more easily the tang shape is changed with a special tool. The important thing during assembly is whether the diameters of both segments are the same. If the difference of diameters is too big, then the sides of both the tang and clevis are flat against each other. When this happens, the inside of the joint can not be seen to access if the joint is good. When the difference in diameters are small, then the tang is slanted against the clevis but, the slant still allows the assembly of the SRB to continue. Another thing that they look for during assembly is if the centers of the segments line up. A difference of +0.25 inches is allowed for mis-aligned segments. If the difference is more than +0.25 then there is a chance of contamination. When the tang and clevis fit together and the centers are off, then there is metal to metal contact. Metal splinters can flake off and can land on the O-ring. The metal segments can also scrape against the O- rings and ruin them. There has been tests that show that contaminates with a size of 0.001 and 0.003 inches in the joint have actually passed a leak test. Thus, there is always a possibility that contamination did actually occur on the SRB of mission 51-L.

On the inside of the tang and clevis there is a gap that needs to be sealed. It is the O-rings that seal this gap. The size of the gap changes as the pressure of gases inside the SRB change. The gap gets bigger when the amount of pressure rises. Gap opening change is called Delta Gap Opening. There are two O-rings, the primary and secondary O-rings. The gap at each O-ring in the aft field joint is different, the gap at the primary O- ring is approximately 0.029 inches, and the secondary is approximately 0.017 inches. During launch the O-ring should move to seal the delta gap opening, and return to its proper state.

by: alina00123

POST COMMENT

Similarity in you and characters on Degrassi episodes Great Stock Picks -pt1 Monthly Phone Deals: Pay Monthly And Take Home Fantastic Mobile Gadgets Ultimate 10 Tips on Tech Gadgets Purchase - How to Let Troubles not Trouble You The Rocking Pop Star Sweethearts Joe Jonas And Demi Lovato Are To Test Their Romance By Hitting The Metal, Plastic And Wooden Hangers How to Treat ADHD Problems Quickly and Naturally Without Side Effects Choosing and Maintaining Duvet Covers What is LLC – Weighing its Pros and Cons Manolo Blahnik And High Heels Different Types and Uses of Tipper on Hire Men's Casual Wear – The Trends and Traditions Flexible Couplings And Its Importance