Mechanical Drawing Assembly Drawing First year mechanical Engineering
Mechanical Drawing Assembly Drawing First year, mechanical Engineering Dept.
1. Air Cook This valve is used to control air or gas supply. The details of an air cock are shown in Fig. 1. It consists of a plug 2 which is inserted into the body 1, from the bottom. The rectangular sectioned spring 4 is placed in position at the bottom of the plug and seated over the screw cap 3. The screw cap is operated to adjust the spring tension. Lever 5 with square hole is used to operate the cock. By a mere 90° turn, the cock is either opened or closed fully.
Fig. 1 Air Cook Draw: 1) half sectional elevation, 2) side view, and 3) plan view.
2. Feed check valve It is used in boilers to regulate the supply of feed water and to maintain the water level. It is fitted close to the boiler shell and in the feed pipe line. Figure 2 shows the details of a feed check valve. The valve prevents water from being returned to the supply line, due to steam pressure in the boiler. Hence, it functions like a non-return valve. It consists of a body with two flanges at right angle and feed water enters at the bottom and enters the boiler through the side opening. The valve seat 5 is introduced into the body of the valve from the top opening. The valve 4 is located in the valve seat, which guides the movement of the valve. The spindle 3 is screwed from bottom of the cover 2 such that, the square end of the spindle projects out through the cover. Studs 8 are screwed to the body and the spindle and cover assembly is fastened to the body by nuts 10. Studs 9 are screwed to the cover and the gland 6 is inserted into the cover and tightened by nuts 11. To prevent the leakage of water through the cover, packing material is introduced between the cover and gland. Hand wheel 7 is located on the spindle such that, the square hole in the hand wheel meshes with the square portion of spindle. The hand wheel is fixed to the spindle by nut 11. By operating the hand wheel, the spindle permits the valve to get lifted from the valve seat and allows feed water to enter the boiler.
Fig. 2 Feed check valve Draw: 1) sectional elevation, 2) side view, and 3) plan view.
3. Spring loaded relief valve Safety or relief valves are used as boiler mountings and they let off steam from inside the boiler whenever the pressure exceeds the set value. Thus, these valves safe guard the boilers. The pressure may be set by using a dead weight or a tension spring with tension adjustment arrangement. Figure 3 shows the details of a spring loaded relief valve in which a tension spring is used to set a pre-determined value for the steam pressure in the boiler. Valve 3 is placed vertically inside the valve body 1 and the valve seat is an integral part of the valve body, in the design considered. Stem 6 is located in the valve, with pointed entering into the valve. Flange 7 is now placed over this assembly and fastened to the valve body by fulcrum bolt 4. Lever 2 is attached to the fulcrum bolt by using the fulcrum pin 5 such that, the lever rests on the stem 6. One end of the tension spring 8 is attached to the lever and the other end to the tension adjusting bolt 9. The tension adjusting bolt is attached to a base and the spring tension can thus be adjusted to any required value.
Fig. 3 Spring loaded relief valve Draw: 1) sectional elevation and 2) side view.
4. C-clamp is used to hold a component for further work, such as inspection or working on it. The part drawings of a C-clamp are shown in Fig. 4. It consists of a frame 1 into which the screw 2 is inserted. The pad 3 is attached to the screw 2 by means of a cheese head cap screw 7. The screw 2 is operated by a tommy bar 4 inserted in the corresponding hole in it. The collar 5 is fitted at the end of the tommy bar, by using the pin 6. The work is clamped between the face of the frame and the pad mounted on the screw.
Fig. 4 C-clamp Draw: 1) sectional elevation and 2) side view.
5. V-belt drive The V-belt drive shown in Fig. 5 is used for converting the V-belt drive from the motor into a gear drive. The main shaft in the unit carries V-pulley at one end and the gear wheel at the other end. The gland 2 is fastened to the bracket 1 by means of the studs 7 and nuts (not shown). The bush 3 is fitted into the bracket and positioned by means of a set screw (not shown). The shaft 4 is introduced into the above assembly and gear wheel 6 is mounted on the left side of the shaft and V-pulley 5 is mounted on the right side by means of woodruff keys (not shown). The gear wheel and Vpulley are fixed in position by means of two nuts (nut shown). The assembly permits free rotation of the shaft in the bracket, and the gland the bush serve as bearings for the shaft.
Fig. 5 V-belt drive Draw: 1) sectional elevation and 2) side view (not showing the V-pulley).
6. Screw jacks are used for raising heavy loads through very small heights. Figure 6 shows the details of one type of screw jack. In this, the screw 3 works in the nut 2 which is press fitted into the main body 1. The tommy bar 7 is inserted into a hole through the enlarged head of the screw and when this is turned, the screw will move up or down, thereby raising or lowering the load
Fig. 6 Screw jack Draw: 1) half sectional elevation and 2) side view.
Thank you mobile no. 01023824824 Prof. Dr. Abdel-Fatah Hashem
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