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UNIT 2 PART B1.(a) Explain the following :(i) Pump characteristic curves(ii) Pump cavitations(iii) Pump noise(iv) Pump selectionNov/dec 2008 (16Marks) 12 a (i,ii,iii,iv)(i) PUMP CHARACTERISTIC CURVESThe control factors for the pump discharge pressure and volume of the fluid are speed of operation and load on the pumpMoreover, pumps of different types will operate differently under similar conditions.For example, the effect of discharge pressure on pump output differs between positive and non positive displacement pumps.The pump characteristic is normally described graphically by the manufacturer as a pump performance curve. The pump curve describes the relation between flow rate and head for the actualpump.

(ii) PUMP CAVITATIONSCavitationmay occur when the local static pressure in a fluid reach a level below the vapor pressure of the liquid at the actual temperature . According tothe Bernoulli Equationthis may happen when the fluid accelerates in a control valve or around a pump impeller.The vaporization itself does not cause the damage - the damage happens when the vapor almost immediately collapses after evaporation when the velocity is decreased and pressure increased.Cavitationis the formation of vapour cavities in a liquid i.e. small liquid-free zones ("bubbles" or "voids") that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid changes ofpressurethat cause the formation of cavities where the pressure is relatively low. When subjected to higher pressure, the voids implode and can generate an intense shockwave.

(iii) PUMP NOISE Noise is a significant factor used to determine the performance of the pumps . Any increase in noise level normally indicates wear and danger of failure of pump . Normally noise is measured in units of decibels (dB) . Generated noise levels depend on many factors such as the pump type, pump component materials, pump mountings, rigidity, manufacturing and fitting accuracy of the pump elements, size and flow capacity, pressure, speed of rotation, pressure pulsations, and the other components in the circuit. It presents the approximate noise levels for various pump designs. Generally speaking, external gear and the piston pumps are the noisiest while screw pumps are very quiet; vane and internal gear pumps have noise levels somewhere in between a piston and screw pumps. Noise levels for various pump designs

Pump type Noise level (dB)Gear 80 -100Vane 65-85Piston 60 - 80Screw 50-70(iv) PUMP SELECTION

2. (b) (i) with a neat sketch, explain the end cushion provided in hydraulic cylinder? (ii) Explain the neat sketch, the principle of operation of telescopic cylinder?Nov/Dec 2008 (16Marks) 12 b (i,ii)(b)(i) CUSHIONING CYLINDERStock load at the ends of travel can be minimized by cushion valves built into the end caps. This is known as cylinder cushioning .Sometimes double acting cylinder contain cylinder cushions to slow down the piston near the ends of the stroke. This reduces the excessive impact load on the end cap. This piston is slowed down when the tapered plunger enters the opening in the end cap. This stops the exhaust free flow from the barrel to port. During the last small fraction of the stroke the fluid has no other way except through a restricted path wit h needle valve. The rate of deceleration is controlled by the adjustable needle valve.

Pneumatic cylinders are capable of very high speed and considerable shock; force can be developed on the end of the stroke. Smaller cylinders often have fixed cushioning i.e. rubber buffers to absorb the shock and prevent internal damage to the cylinder On large cylinders, the impact effect can be absorbed by an air cushion that decelerates the piston over the last portion of the stroke. This cushion traps some of the exhausting air near the end of the stroke before allowing it to bleed off more slowly through the adjustable needle valve.The normal escape of the exhausting air to the outlet port is closed off as the cushion nose enters the cushion chamber, so that air can only escape through the adjustable restriction port. The trapped air is compressed to a relatively high pressure which breaks the inertia of the piston.

(ii) TELESCOPIC CYLINDERTelescopic cylindersare a special design of ahydraulic cylinderorpneumatic cylinderwhich provide an exceptionally long output travel from a very compact retracted length. Typically the collapsed length of a telescopic cylinder is 20 to 40% of the fully extended length depending on the number of stages.Some pneumatic telescoping units are manufactured with retracted lengths of under 15% of overall extended unit length. This feature is very attractive to machine design engineers when a conventional single stage rod styleactuatorwill not fit in an application to produce the required output stroke.Heavy duty telescopic cylinders are usually powered byhydraulics, whereas some lighter duty units could also be powered bycompressed air. Telescopic cylinders are also referred to as telescoping cylinders and multi-stage telescopic cylinders.An application for telescopic cylinders commonly seen is that of thedump bodyon adump truckused in aconstructionsite. In order to empty the load ofgravelcompletely, the dump body must be raised to an angle of about 60 degrees. To accomplish this long travel with a conventional hydraulic cylinder is very difficult considering that the collapsed length of a single stage rod cylinder is approximately 110% of its output stroke.It would be very challenging for thedesign engineerto fit the single stage cylinder into thechassisof the dump truck with the dump body in thehorizontalrest position. This task is easily accomplished, however, using a telescopic style multi-stage cylinder.

Single acting telescopic cylinders are the simplest and most common design. As with a single acting rod style cylinder, the single acting telescopic cylinder is extended using hydraulic or pneumatic pressure but retracts using external forces when the fluid medium is removed and relieved to thereservoir.

3. (a) Draw a neat sketch of an unbalance type vane pump, explain its construction and operation and also show how the same can operate as a reversible pump. Also given its standard graphical symbol?May/June 2009 (16Marks) 12 (a)The rotor contains radial slots. The rotor is splinted to the drive shaft and rotates inside a cam ring. Vanes are fit and sliding in the slots of the rotor and they are carried around by. the rotor. These vanes are kept in continuous contact with the cam surface by centrifugal force (or) by springs. The rotor is offset within the pump housing i.e There is an eccentricity between' the centre of rotor and centre of cam rings. If the eccentricity is zero, there is no flow. 'During one-half revolution of the rotor, the volume increases between the rotor and cam ring. The resulting volume expansion causes a reduction of pressure ie., vacuum. This vacuum causes the fluid to flow through the inlet port. When the rotor rotates through second half revolution

When a hydraulic pump operates, it performs two functions. First, its mechanical action creates avacuumat the pump inlet which allows atmospheric pressure to force liquid from the reservoirinto the inlet line to the pump. Second, its mechanical action delivers this liquid to the pump outlet and forces it into the hydraulic system.A pump produces liquid movement or flow:it does not generate pressure. It produces the flow necessary for the development of pressure which is a function of resistance to fluid flow in the system. For example, the pressure of the fluid at the pump outlet iszero for a pump not connected to a system (load). Further, for a pump delivering into a system, the pressure will rise only to the level necessary to overcome the resistance of the load. The pump illustrated in is unbalanced, because all of the pumping action occurs in the chambers on one side of the rotor and shaft. This design imposes a side load on the rotor and drive shaft. This type vane pump has a circular inner casing. Unbalanced vane pumps can have fixed or variable displacements. Some vane pumps provide abalancedconstruction in which an elliptical casing forms two separate pumping areas on opposite sides of the rotor, so that the side loads cancel out, Balanced vane pumps come only in fixed displacement. In a variable-volume unbalanced design, , the displacement can be changed through an external control such as a hand wheel or a pressure compensator. Adjustment of the compensator spring determines the pressure at which the ring shifts.Because centrifugal force is required to hold the vanes against the housing and maintain a tight seal at those points, these pumps are not suited for low-speed service. Operation at speeds below 600 rpm is not recommended. If springs or other means are used to hold vanes out against the ring, efficient operation at speeds of 100 to 200 rpm is possible.They may be of the same or different sizes. Although they are mounted and driven like single pumps, hydraulically, they are independent. Another variation is the series unit: two pumps of equal capacity are connected in series, so that the output of one feeds the other. This arrangement gives twice the pressure normally available from this pump. Vane pumps have relatively high efficiencies. Their size is small relative to output. Dirt tolerance is relatively good.4. (b) (i) Describe the working principle of external gear pump with a diagram? (ii) Explain briefly about the fluid motors?May/June 2009 (16Marks)12 b (i,ii)(b)(i) EXTERNAL GEAR PUMPThe simplest type of positive displacement pump is external gear pump it consist of just two closely meshing gears which rotate as shown in fig.This pump creates flow by carrying liquid between the teeth of two meshing gears. Here one gear is connected to the drive shaft which is connected to the motor. This gear is known as driver gear. Another gear is meshing with the drive gear. When the teeth come out of mesh, a' vacuum is created so that the liquid is drawn. in this suction side .. Liquid is trapped in between the outer teeth and the pump housing and transferred from inlet side to outlet side where it is discharged to the system.The displacement of the gear pump is determined by Volume of fluid between each pair of teeth Number of teeth Speed of rotation The. performance of gear pump is limited by leakage and the ability of the pump. to withstand the differential pressure between inlet and outlet ports. The gear pump requires closely meshing gear. However, there should be minimum clearance- between teeth tip and pump housing. As a result,some of the liquid. may leak directly from outlet port to' inletport. This internal leakage " is known as pump slippage.Hence the actual flow rate QA is The gear pumps are used at pressure upto 150 bar and capacities of around 675 l/m. the voumentric effienceincy of gear pump is generall at 90% which is the lowest of three types of pumps.The herringobone gears consitst of two rows of heleical teeth which cance out the thrust force. This gears can be used for developing much high pressure

(ii) FLUID MOTORSFluid poweris the use of fluids under pressure to generate, control, and transmit power. Fluid power is subdivided intohydraulicsusing a liquid such asmineral oilorwater, andpneumaticsusing a gas such as air or other gases. Compressed-air and water-pressure systems were once used to transmit power from a central source to industrial users over extended geographic areas; fluid power systems today are usually within a single building or mobile machine.A fluid power system has a pump driven by a prime mover (such as an electric motor orIC engine) that converts mechanical energy into fluid energy. This fluid flow is used to actuate a device such as: AHydraulic cylinderorPneumatic cylinder, provides force in a linear fashion AHydraulic motororPneumatic motor, provides continuous rotational motion ortorque A Rotary actuator provides rotational motion of less than 360 degrees.

5. (a)(i) how much hydraulic power would a pump produce when operating at 125 bars and delivering 1.25lps of oil? What power rated electric motor would be selected to drive this pump if its overall efficiency is 88%? (ii) What are the factors to be considered in selection of a pump?April/May 2008 (16 Marks) 12 a (i,ii)Given Data:Pressure, P=125 bars =125x10^5 N/m2QA=1.25 Lps=1.25 x 10^-3m3/sec.Overall Efficiency= 88%Solution :

1. Hydraulic power= P x QA= (125 x 10^5) x (1.25x10^-3)= 15.625W2. Brake Power = Hydraulic power/ over all efficiency= (15.625 x 10^3)/0.88= 17758W(ii) FACTORS TO BE SELECTION OF A PUMP

Refer question No 1 a (iv)

6. (b) (i) Explain with neat sketch, the principle and operation of telescopic cylinder. (ii) With respect to hydraulic motors, define the following terms:1. volumentric efficiency2. mechanical efficiency3. overall efficiencyApril/May 2008 16 Marks 12 b(i,ii)b. (i) TELESCOPIC CYLINDERRefer question No. 2 b (ii) (ii) HYDARULIC MOTORS 1. Volumetric efficiency The volumetric efficiency of a hydraulic motor is the inverse of that for a pumpv = theoretical flow rate motor should consume / Actual flow rate consumed by motorv = (QT/QA) X 100

2. Mechanical efficiencyThe mechanical efficiency of a hydraulic motor is the inverse of that for a pump.v = (actual torque delivered by motor)/(torque motor should theoretically deliver)v = (TA/TT) x 100TA= (Actual power delivered by motor)/(Angular speed of motor shaft)=P/T=(VD X P)/ 2

3. Overall efficiencyThe overall efficiency of the hydraulic motor is the product of the volumetric and mechanical efficiencies o = v x mech

7. (a)(i) Enumerate the working principle of balanced vane pump with neat sketch. Also write the advantages and disadvantages. (ii) Find the offset angle for an axial piston pump that delivers 1.25 lps at 2000 rpm. The pump has nine 12.7mm diameter pistons arranged on a 130 mm diameter piston circle. The volumetric efficiency is 94%Nov/dec 2010 (16 marks) 12 a(i,ii)(i) BALANCED VANE PUMPBalanced vane pump have two lobes on the earn surface oil opposite sides of the shaft. The earn surface, instead of being circular, is roughly elliptical, so that each vane makes two strokes on each revolution of the shaft. This pump has 'two intake ports and two outlet ports diametrically opposite to each other. Thus, the pressure ports are opposite to each other and a complete' hydraulic balance is achieved. Since the earn ring is an elliptical one, it forms two separate pumping chambers on opposite sides of the rotor. So the side load produced by one charnber is exactly balanced by an equal side load from the other chamber. Thus, the bearing loads from internal pressure are zero and it permits the higher operating pressures. Balanced vane pumps have much improved service lives than unbalanced vane pumps. Balanced vane pumps, due to its symmetrical constructions, are difficult to design as a variable displacement pumps. These vane pumps costs a little more than the gear pumps of comparable quality. Bearing loads are low (zero) Vane pumps are more sensitive to dirt than gear pumps. Despite the different configurations, most vane pumps operate under the same general principle described below.1. A slotted rotor is eccentrically supported in a cycloidal cam. The rotor is located close to the wall of the cam so a crescent-shaped cavity is formed. The rotor is sealed into the cam by two side plates. Vanes or blades fit within the slots of the impeller. As the rotor rotates (yellow arrow) and fluid enters the pump, centrifugal force, hydraulic pressure, and/or pushrods push the vanes to the walls of the housing. The tight seal among the vanes, rotor, cam, and sideplate is the key to the good suction characteristics common to the vane pumping principle.2. The housing and cam force fluid into the pumping chamber through holes in the cam (small red arrow on the bottom of the pump). Fluid enters the pockets created by the vanes, rotor, cam, and sideplate.3. As the rotor continues around, the vanes sweep the fluid to the opposite side of the crescent where it is squeezed through discharge holes of the cam as the vane approaches the point of the crescent (small red arrow on the side of the pump). Fluid then exits the discharge port.


8. (b) (i) What is the purpose of cushioning cylinder? (ii) A hydraulic motor has a displacement of 150cm3 and operates with a pressure of 85 bars and a speed of 1800 rpm. If the actual flow rate consumed by the motor is 5 Lps and the actual torque delivered by the motor 185 N-m find 1. Volumetric efficiency 2. Mechanical efficiency 3. Over all efficiency 4. kW power delivered by the motor. (iii) Define the terms used to evaluate the performance of hydraulic motorNov/Dec 2010 (16 Marks) 12 b (I,ii)(i) CUSHIONING CYLINDER

Refer question No. 2 b (i)



Refer question No. 6 b (ii)

9. (a)(i) Explain the working principle of double acting cylinder with neat sketch. (ii) How are the pumps classified? Explain with suitable sketch the working of unbalanced vane pump?Nov/Dec 2011 16 marks 12 a (i,ii)(i) DOUBLE ACTING CYLINDERAdouble-acting cylinderis a cylinder in which the working fluid acts alternately on both sides of the piston. In order to connect the piston in a double-acting cylinder to an external mechanism, such as acrank shaft, a hole must be provided in one end of the cylinder for the piston rod and this is fitted with aglandor 'stuffing box' to prevent escape of the working fluid. Double-acting cylinders are common in steam enginesbut unusual in other engine types. Many hydraulic and pneumatic cylinders use them where it is needed to produce a force in both directions.A double-acting cylinder is a cylinder in which the working fluid acts alternately on both sides of the piston. It has a port at each end, supplied with hydraulic fluid for both the retraction and extension of the piston. A double-acting cylinder is used where an external force is not available to retract the piston or where high force is required in both directions of travel.The double acting cylinder is more common than the single acting cylinder. It works at any angle and in almost any application where hydraulic power is needed. Even with applications where gravity (or weight) can assist retraction, hydraulic pressure is often applied to control acceleration, change the rate of travel and cushion the stoppage. Travel in one direction always differs from travel in the other, all things being equal; the push action requires more force and is slower but more work output is generated. The pulling action is faster, but less work output is created.If you are looking to source a standard double-acting cylinder, we have widespread, competitive access to both leading and niche cylinder manufacturers from around the world. The link above shows just some of the manufacturersand other brands that we can supply.

(ii) TYPES, UNBALANCED VANE PUMPSA pump converts mechanical energy into hydraulic energy. The mechanical energy is given to the pump by nil electric motor. Due to mechanical action, the pump creates" partial vacuum at its inlet. This makes the atmospheric pressure to force the liquid through the inlet Line and into the pump." The pump then pushes the liquid into the hydraulic system. The pumps are classified as (i) Positive displacement pumps (ii) Hydrodynamic (or) Non-positive displacement pumps The following are the three main types of positive displacement pumps. 1. Gear Pumps . 2. VanePumps 3. Piston Pumps Gear Pumps are further classified as (i) External -Gear Pump(ii) Internal gear pump(iii) Lobe pump(iv) Screw pump(v) Gerotor pumpVane pumps are further classified as1. Unbalanced vane pump2. Balance vane pump3. Variable displacement vane pumpPiston pumps1. radial piston pump1. Piston pump with stationary cam and rotating block2. Axial pump with swash plate 3. Bent axis pumpUNBALANCED VANE PUMPS Refer Question No. 3 a

10. (b)(i) Explain the working principle of external gear pump and determine its performance measures? (ii) What are the factors to be considered in the selection of a pump?Nov/Dec 2011 (16 Marks) 10 b (I,ii)(b)(i) EXTERNAL GEAR PUMPRefer Question No. 4 b (i) (ii) SELECTION OF PUMP Refer Question No. 1 a (iv)11.a)(i) Explain how positive displacement pumps build pressure compared to rotodynamic pumps. What are the advantages of positive displacement pumps? (ii) using a neat sketch explain the construction and operation of an axial piston pump of swash plate type?(i) Pumps are devices that increase the static pressure of fluids. In other words, pumps add energy to a body of fluid in order to move it from one point to another. The increase in static pressure can be achieved in different ways. It describes various pumps by which this result can be achieved and the characteristics of such pumps.Positive displacement pumps are those in which the moving element of the pump forces a fixed volume of fluid from the inlet pressure section of the pump into the discharge zone of the pump resulting in an increase in the pressure of the liquid. Such pump types are seldom used for highway storm water pump stations and are not discussed furtherAdvantages In general, positive displacement pumps are ideal for applications where a constant flow is needed. They create medium to high pressure and are often an excellent way to pump oils and other viscous fluids. Positive displacement pumps are also extremely useful for applications requiring a combination of low flow and high pressure. (ii) AXIAL FLOW PISTION PUMP Aswashplateis a device used inmechanical engineeringto translate the motion of a rotating shaft into reciprocating motion, or to translate a reciprocating motion into a rotating one to replace thecrankshaftin engine designs.A swashplate consists of a disk attached to a shaft. If the disk were aligned perpendiular to the shaft, then rotating the shaft would merely turn the disk with no reciprocating (orswashplate) effect. But instead the disk is mounted at an oblique angle, which causes its edge to appear to describe a path that oscillates along the shaft's length as observed from a non-rotating point of view away from the shaft. The greater the disk's angle to the shaft, the more pronounced is this apparent linear motion. The apparent linear motion can be turned into an actual linear motion by means of a follower that does not turn with the swashplate but presses against one of the disk's two surfaces near its circumference. The device has many similarities to thecam.theswashplate engineuses a swashplate in place of a crankshaft to translate the motion of a piston into rotary motion.Internal combustion enginesandStirling engineshave been built using this mechanism.Theaxial piston pumpdrives a series of pistons aligned coaxially with a shaft through a swashplate to pump a fluid. Ahelicopter swashplateis a pair of plates, one rotating and one fixed, that are centered on the main rotor shaft. The rotating plate is linked to the rotor head, and the fixed plate is linked to the operator controls. Displacement of the alignment of the fixed plate is transferred to the rotating plate, where it becomes reciprocal motion of the rotor blade linkages. This type of pitch control, known as cyclic pitch, allows the helicopter rotor to provide selective lift in any direction. Nutating flowmetersand pumps have similar motions to the wobble of a swashplate, but do not necessarily transform the motion to a reciprocating motion at any time.

12.b) explain using a neat sketch end cushioning provided in hydraulic cylinders also sketch at least six types of cylinder mounts available.CUSHIONING CYLINDER Refer Question No. 2 b (i)

13.a) Classify the positive displacement pumps and describe the constructional features of screw pumps.Refer Question No. 11 a (i) Ascrew pumpis a positive displacement pump that use one or several screws to move fluids or solids along the screw(s) axis. In its simplest form (theArchimedes' screw pump), a single screw rotates in a cylindrical cavity, thereby moving the material along the screw'sspindle. This ancient construction is still used in many low-tech applications, such asirrigation systemsand in agricultural machinery for transporting grain and other solids.Development of the screw pump has led to a variety of multiple-axis technologies where carefully crafted screws rotate in opposite directions or remains stationary within a cavity. The cavity can be profiled, thereby creating cavities where the pumped material is "trapped".In offshore and marine installations, a three spindle screw pump is often used to pump high pressureviscous fluids. Three screws drive the pumped liquid forth in a closed chamber. As the screws rotate in opposite directions, the pumped liquid moves along the screws spindles.Three-Spindle screw pumps are used for transport of viscous fluids with lubricating properties. They are suited for a variety of applications such asfuel-injection,oil burners, boosting,hydraulics, fuel,lubrication, circulating, feed and so on.Compared tocentrifugal pumps, positive displacements (PD) pumps have several advantages. The pumped fluid is moving axially without turbulence which eliminates foaming that would otherwise occur in viscous fluids. They are also able to pump fluids of higher viscosity without losing flow rate. Also, changes in the pressure difference have little impact on PD pumps compared to centrifugal pumps.The term screw pump is often used generically. However, this generalization can be a pitfall as it fails to recognize the different product or screw configurations, as well as the uses, advantages and design considerations for each. The design differences of each screw configuration and pump type make each suitable for different applications and handling fluids with varying characteristics.Each screw pump operates on the same basic principal of a screw turning to isolate a volume of fluid and convey it. However, the mechanical design of each is different. The primary difference in one, two, three or multiple screw pumps.

14. b) What are the different types of fluid motors? Also explain the function them?Refer Question No. 4 b (ii) 2 b(ii)Fluid power actuators receive fluid from a pump (typically driven by an electric motor). After the fluid has been pressure, flow, and directionally controlled, the actuator converts its energy into rotary or linear motion to do useful work. Cylinders account for more than 90% of the actuators used in fluid power systems for work output. Of the approximately 10% of actuators that produce rotary output, more than 90% are hydraulic motors, while the rest are some form of rotary actuator.Single-acting ram cylindersThe symbols and cutaway views inFigure. show single-acting ram cylinders in push and pull types. Rams can be as small and simple as a service station lift operated by air over oil, or as big and complex as a 100,000-ton extrusion press.Single-acting rams often are mounted vertically up and are weight returned. When a ram cylinder is mounted vertically down or horizontally, it must have some method of retracting it to the home position.Figure shows one method. Small single-acting pull rams -- mounted alongside the large working ram -- raise and hold it in the up position with a counterbalance valve (not shown). A directional valve or a bi-directional pump directs fluid to the push or pull rams to make them cycle. Another retraction method uses single-acting push rams that oppose the platen movement from the opposite side. (For a circuit that uses a large-diameter vertical down acting ram cylinder, see Figure. Small ram cylinders may be returned manually or via a spring.

Ram cylinders only have seals where the ram passes through the body. Anytime a ram cylinder drifts from its stopped position, the cause is valve or pipe leakage if no fluid is coming out around the ram seal.As the ram moves, stops and guide protrusions on it keep it aligned and indicate maximum stroke. Usually on large-area rams, the stops tear off the packing gland and bushing retainers if the ram is not stopped some other way. Most machines using rams have other methods to keep them from overstroking. (Some only have warning placards about problems if the ram is powered beyond certain limits.) The guide protrusions and bushing align the ram in its housing so it runs true.Figure shows another type of ram cylinder. When there is a need for a long-stroke actuator with a short retracted length, one option is a telescoping cylinder.15.a (i) with a neat sketch, explain the construction and working principle of an external gear pump? (ii) a pump having a displacement of 80 cm3, delivers oil at the rate of 1.25 lps at 1200 rpm and 75 bar.if the prime mover input torque is 90 N-m calculate the overall efficiency of the pump and the theoretical torque require to operate the pump.(i) Refer Question No. 4 b(i) (ii)

16.b(i) with a neat sketch, explain the construction and cushioning mechanism in a cylinder. (ii) with a neat sketch, explain the working principle of balanced vane pump.(i) Refer Question No. 2 b(i)(ii) Refer question No. 7 a (i)17.a)(i) Explain the construction and working of an swash plate type piston pump with neat sketch? (ii) Write a short notes on Telescopic cylinder?(i) Refer question No. 11 a(ii)

(ii) Refer Question No. 2 b(ii)18.b)(i) Explain the working of gear type motor and vane type motor? (ii) Explain the cushioning of cylinder?(i) Refer Question No. 4 b (ii) and 3 a(ii) Refer Question No. 2 b(i)