UPMRC Fitter Maintainer (Civil) Paper with solution -2021

Answer.3. Carbon exists as free graphite flakes

Explanation

Cast iron is a very common engineering material. It is always used in the form of castings. It cannot be rolled, drawn or forged because it has very low ductility and is brittle.

Grey cast iron: Most castings in use are of this type, in which the free carbon is in the form of graphite flakes. These flakes make the fractured surface appear grey and render the cast iron brittle and less ductile. The graphite also makes the casting soft and machinable.

Answer.4. Rectangular pulley

Explanation:-

A drive pulley is a pulley that is attached to a power source, that when in use puts force on a belt (or cable or chain). Pulley is used for mechanical power transmission.

Types of Pulleys

Various types of pulleys are in use and designed for specific applications. However, the following types of pulleys are extensively used.

1. Split pulley
2. Stepped pulley
3. Solid pulley
4. Fast and loss Pulley
5. Guide pulley
6. Jockey pulley
7. Grooved Pulley

Solid pulleys

A solid pulley is made by casting and in a single piece. It is commonly made of cast iron and normally smaller in size. These pulleys are mounted on the shaft by inserting from one end through the hub and the key is inserted from one end to fix it with the shaft.

Split pulleys

Split pulleys are similar to solid pulleys but are made into two halves. These two halves are joined together by nuts and bolts.  Pulleys are split into two halves only to make them easily mounted in the assembly without removing other components. The arms of the pulley are screwed with the hub and rim on the other end. These pulleys are commonly fabricated from wrought iron or mild steel and are relatively stronger and lighter in weight.

Stepped or cone pulleys

These pulleys are used when the velocity of the driven shaft needs to be changed frequently. These pulleys are extensively used in machine tools such as lathe, drilling machine, milling machine, shapper, etc. Stepper pulleys provide a velocity ratio between the driving shaft to the driven shaft in fixed steps, whereas in cone pulleys, these steps are continuously variable as required. 

Answer.4. One digital counter

Explanation:-

Vernier Calipers used for measuring outside dimensions, inside dimensions, and depth measurements, all in one tool. They have a graduated bar with markings like a ruler.

Digital vernier calipers with a resolution (least count) of 0.01 mm are employed for quick and error-free measurements as the instruments digitally display measured valve and also provide many additional functions which are not available in conventional vernier calipers. Digital Vernier caliper consists of One digital counter.

WORKING OF DIGITAL CALIPER

Reference point setting (zero settings): The measuring faces are closed gently and a clear button is pressed. Power is then switched on and zero is set.

Absolute value measurements: After zero setting, the instrument can measure the absolute values of the inside, outside, depth, and step dimensions.

Comparative measurements: Press the clear button at a given dimensional value. The display will be set to 0.00 mm for comparative measurements.

Answer.1. Caliper

Explanation:-

Calipers:-

These are non-precision linear measuring instruments used to transfer and compare a dimension from one object to another or from one part to a micrometer or to a scale.

Answer.3. 10000 cu. ft.

Explanation:-

Ventilation

Adequate ventilation must be provided for all welding, cutting, brazing and related operations. Adequate ventilation means sufficient ventilation so that hazardous concentrations of airborne contaminants are below the allowable levels specified. Adequate ventilation depends on many factors including the following:

1. Volume and configuration of the space where welding occurs.
2. Number and type of operations generating contaminants
3. Allowable levels of specific toxic or flammable contaminants being generated.
4. Natural airflow and general atmospheric conditions where work is being done.
5. Location of welders’ and other persons’ breathing zones in relation to the contamination, contaminants, or sources.

Adequate ventilation can be obtained by using the following, either singly or in combination:

1. Natural ventilation
2. General mechanical ventilation
3. Local exhaust ventilation

Natural ventilation occurs when the welding is done out of doors. Natural ventilation can occur indoors, but only if the welding shop is sufficiently large. This means a space of 10,000 cu. ft. (284 cu. meters) per welder, with a ceiling height of more than 16 ft. (5 meters), and does not contain partitions, balconies, or other structural barriers that obstruct ventilation. Natural ventilation must be supplemented when welding on hazardous materials.

General mechanical ventilation using roof exhaust fans, wall exhaust fans, or similar air movers must be used if the space per welder is less than 10,000 cu ft. (284 cu meters), or if the ceiling height is less than 16 ft. (5 meters), or if the shop includes partitions, balconies, or other structural barriers that obstruct cross ventilation. General mechanical ventilation is recommended to maintain a low level of airborne contaminants and to prevent the accumulation of explosive gas mixtures.

If general mechanical ventilation is not sufficient to maintain the general background level of airborne contaminants below the recommended limits, then local exhaust ventilation or local forced ventilation is required.

Ventilation should consist of ventilation systems or local exhaust systems and should be used when:

• A space is less than 10,000 cubic feet (284 m³) per welder.
• In a room having a ceiling height of less than 16 feet (5 m).
• In confined spaces or where cross ventilation is reduced from partitions, balconies, or other structural barriers.

Answer.2. Aluminum

Explanation:-

Cutting holes in a workpiece 1s done by using a rotating cutting tool called a drill, or drill bit. 

In a drilling application, HSS(High-Speed Steel) material is normally used due to its cheaper price than other materials like tungsten carbide, ceramic, or PCD. HSS or carbide drill bits have primary attraction based on better performance at high cutting speed compared with other drill bits.

The HSS aluminum drill operated at the highest cutting speed.

Speed for Carbide drills

Answer.2. Hot Water

Explanation:-

A soldering iron is a copper rod with a thin tip, which can be used for flattening the soldering material. The soldering iron can be heated by keeping in a furnace, Bunsen burner or by means of an internal electrical resistance whose power rating may range from 15 W for electronic applications to 200 W for sheet-metal joining. This is the most convenient method of soldering but somewhat slower compared to the other methods.

In dip soldering, a large amount of solder is melted in a closed tank. The parts that are to be soldered are first cleaned properly and dipped in a flux bath as per the requirement. These are then dipped into the molten solder pool and lifted with the soldering complete.

Wave soldering is a variant of this method wherein the part to be soldered (e.g.. an electronic printed circuit board, PCB) is not dipped into the solder tank. but a wave is generated in the tank so that the solder comes up and makes the necessary joint. This is normally a continuous process with the PCBs being continuously moving on top of the solder tank and the waves being continuously generated. lt is used for the mass production of electronic equipment. There are also other methods available for solderings, such as torch soldering, oven soldering, resistance soldering, induction soldering, and infrared soldering.

Answer.4.100

Explanation

Feeler gauges, also known as thickness gauges consist of several thin hardened strips, blades, or leaves. 

The length of the feeler gauge blade as per the feeler gauge blade is 100 mm. The blade material for the feeler gauge is Stainless steel.

Feeler gauges generally comprise a series of gauging blades of different grades and thicknesses from 0.03 mm to 1 mm. The blades are made of heat-treated bright polished tool steel having a tensile strength of about 170 kgf/cm² for thickness up to 0.5 mm and about 70 kgf/cm² for thickness up to 0.5 mm and above.

Answer.2. The distance traveled by the screw / Number of complete rotations

Explanation:-

The linear distance moved by the screw head during one complete rotation of the screw is called the pitch. It is also equal to the distance (along its axis) between two successive threads on the screw. 

Then pitch of the screw can be found by the formula, Pitch

Pitch = distance traveled by the screw / Number of complete rotations

Answer.1. Chromium and Nickel

Explanation:-

Stainless Steel: It is an alloy of steel containing chromium as the principal alloying element along with other elements like Nickel and Manganese, etc. Generally, chromium present in stainless steel is about 12%. The chromium present in stainless steel reacts with oxygen present in the atmosphere and makes a strong layer of chromium oxide which is highly corrosive resistant in nature.