Reciprocating and gear pumps (with elements 2 terms)

rotary pump

is a positive displacement pump designed to move fluids efficiently by trapping and displacing fixed volumes of liquids

gear pump

is a rotary pump that helps move liquids using built-in gears. This kind of pump has two or more gears that work together to create a vacuum in the suction side,

external gear pump

consists of two identical, interlocking gears supported by separate shafts. Generally, one gear is driven by a motor and this drives the other gear (called the idl

internal gear pump

works in a similar way, but the two gears that mesh are of different sizes, and one turns inside the other. The bigger gear with teeth that stick out from the inside acts as the rotor and the smaller inner gear acts as the idler

Prime Mover

is the motor or engine used to turn the shaft that holds the driver gear in the gear pump. It is the source of power of the pump.

Driver or Power Gear

is The gear that is attached to a shaft that is rotated by a prime mover.

Driven Gear or Idler gear

is the gear that meshes with driver gear. It spins at the same rate as the power gear.

Casing

is pump housing that contains both the power gear and the idler gear.

Suction Port

is This component allows liquid to enter the pump. The inlet section where the pump receives liquid at low pressure.

Discharge Port

is This section delivers compressed liquid to the required destination. The point where the pump's high-pressure liquid is discharged.

Safety Valve/ Pressure Relief Valve

is This valve, located on the pump's outlet, allows for the release of fluid in the way of higher pressure, protecting the pump from malfunctioning.

Housing seal

is mounted to prevent dirt and liquids from getting into the bearing and contaminating the lubricant.

Bushings

is helps to lessen friction between the two gears.

Mounting Flanges

are used to connect valves, pipes, pumps, and other pieces of equipment to make a pipework system.

Bearings

allows rotation and bears the load of the pump.

Clearance Gap

is usually refers to the distance between the stationary and rotating component of the pump.

Internal Gear

is the gear with internal teeth connected to the motor shaft.

External Gear

is driven by internal gear and mounted eccentrically with respect to internal gear.

Crescent Shaped Separator

is the crescent shaped spacer provided in the casing. It is the stationary part around which the liquid is carried.

volumetric displacement, 𝑉𝐷,

is the theoretical volume of fluid displaced per one rotation of the gear.

Slip

is the quantity of fluid leaking through internal clearances. It is not affected by pump speed but is a result of viscosity, pressure, and available space to pass through.

Mechanical efficiency

is the ratio of the ideal hydraulic power output of the pump to the actual shaft power required to drive the pump.

Piston pump

uses a piston as the reciprocating member.

Plunger pump

uses a plunger as the reciprocating member.

Diaphragm pump

uses an elastic membrane as the reciprocating member.

Single-acting reciprocating pump

uses one side of the piston to promote flow.

Double-acting reciprocating pump

uses both sides of the piston to promote flow.

Simplex pump

is a pump having a single cylinder.

Duplex pump

is a pump having two cylinders.

Triplex pump

is a pump having three cylinders.

Direct-acting

is a pump activated by the force from a steam piston.

Indirect-acting

is a pump activated by an electric motor, an internal combustion engine or turbine.

Suction Pipe

connects the cylinder of the reciprocating pump to the liquid source.

Suction Valve

is a one-directional flow valve placed between suction pipe inlet and the cylinder. It is open during the suction stroke and closed during the discharge stroke.

Delivery Pipe

connects the pump cylinder to the point of discharge.

Delivery Valve

is a non-return valve placed between cylinder and the discharge pipe. It is closed during the suction stroke and open during the discharge stroke.

Cylinder

is a hollow case that is filled with the liquid to be pumped.

Piston

is the part that moves in a reciprocating motion inside the cylinder causing both suction and discharge.

Piston Rod

is the part that transmits power to the piston.

Piston Ring or Seal

are gaskets that form a seal assembly, preventing the liquid to be pumped from leaking into the cylinder as the piston moves.

Crank

is a circular disk attached to the motor; it is used to transfer the rotary motion of the motor to the piston.

Connecting Rod

acts as a translator, converting the rotational motion of the crank to reciprocating motion of the piston.

Crosshead

is the part that connects the piston rod to the connecting rod. It keeps the piston rod parallel to the axis of the cylinder.

Strainer

is a device that provides a means of removing solids from the flowing fluid in the suction pipe with the purpose of protecting the pump equipment and processes.

Air Vessel

is a closed chamber connected to both suction and delivery pipes to eliminate frictional losses and promote uniform discharge.

Bore clearance

Greater clearance around the outside diameter of the gear = more slip.

Side Clearance

Greater clearance between the gear and bearing or liner plate = more slip.

Liquid viscosity

Lower viscosity (thinner liquid) = more slip.

Differential Pressure

Higher differential pressure (discharge pressure - inlet pressure) = more slip.

Volumetric displacement (VD)

the theoretical volume of fluid displaced per one rotation of the gear.

Circular pitch (Pc)

is the distance from the center of one tooth the center of the next tooth, measured on the pitch circle.

Module (M)

is used with SI units and is the ratio of the pitch-circle diameter (D) of a gear in millimeters to the number of teeth (n).

Bi-directional (for Internal Gear pump)

the pump is capable to work in both directions, without any modification.

Gears

Are toothed members which transmit power / motion between two shafts or between a shaft and a slide by meshing without any slip.

Positive drives

Gear drives are also called

Pinion

In any pair of gears, the smaller one is called

Gear (Bull gear)

In any pair of gears, the larger one is called

Spur gears

Are widely used in parallel shaft applications, such as transmissions, due to their low cost and high efficiency. The design allows for the entire gear tooth to make contact with the tooth face at the same instant.

Spur gears

This type of gearing tends to be subjected to high shock loading and uneven motion. Design limitations include excessive noise and a significant amount of backlash during high-speed operation.

Helical gears

Differ from spur gears in that their teeth are not parallel to the shaft axis; they are cut in a helix or angle around the gear axis. During rotation, parts of several teeth may be in mesh at the same time, which reduces some of the loading characteristics of the standard spur gear.

Herringbone gears

Are an improvement over the helical gear design. This gears are actually double helical gears with teeth angles reversed on opposite sides. This causes the thrust produced by one side to be counterbalanced by the thrust produced by the other side. The two sets of teeth are often separated at the center by a narrow gap for better alignment and to prevent oil from being trapped at the apex.

Herringbone gears

Are capable of transmitting large amounts of power and are frequently used in power transmission systems. These gears are best suited for quiet, high-speed, low-thrust applications where heavy loads are applied. Large turbines and generators frequently use these gears because of their durability.

Internal gears

Are used for transmitting power between two parallel shafts. In these gears, annular wheels have teeth on the inner periphery which makes the drive very compact. In these drives, the meshing pinion and annular gear are running in the same direction. Their precision rating is fair. They are useful for high load and high-speed application with high reduction ratio.

Rack

Is a segment of a gear of infinite diameter and the tooth profile can be spur or helical. This type of gearing is used for converting rotary motion into translatory motion or vice versa

Bevel gears

(Straight and spiral cut) transmit motion between shafts that are at an angle to each other. Primarily found in various types of industrial equipment as well as some automotive applications (differentials), they offer efficient operation and are easy to manufacture.

Spiral gears

Are also known as crossed helical gears; they have a high helix angle and transmit power between two non-intersecting non-parallel shafts. Their point of contact comes under the conditions of considerable sliding velocities; hence, their precision rating is poor. They are used for light load and low speed application such as instruments, sewing machines etc.

Hypoid gears

Are a form of bevel gears designed to operate on non-intersecting axes. They offer improved efficiency and higher ratios over traditional straight bevel gears. Commonly found in axle differentials, these gears are used to transmit power from the driveline to the axle shafts.

Worm gear

Sets employ a specially-machined

Planetary gear

Such as those found in automatic transmissions, provide the different gear ratios needed to propel a vehicle in the desired direction at the correct speed. Gear teeth remain in constant mesh, which allows for gear changes to be made without engaging or disengaging the gears, as is required in a manual transmission. Instead, clutches and bands are used to either hold or release different members of the gear set to get the proper direction of rotation and/or gear ratio.

Addendum circle

The imaginary circle drawn through the tips of the gear teeth, concentric with the pitch circle. It defines the outermost boundary of the gear teeth

Dedendum circle

The imaginary circle drawn through the bottoms of the gear tooth spaces, also known as the root circle. It is located inside the pitch circle.

Pitch circle

An imaginary circle that represents the location where two mating gears effectively contact and roll without slipping. It is the fundamental reference circle for gear calculations.

Pitch diameter

Is the diameter of the pitch circle. This circle is theoretical circle upon which all computations are made.

Face Width

The width of the gear tooth measured parallel to the gear’s axis. It determines the surface area of contact between meshing teeth.

Pitch surface

The imaginary surface generated by the pitch circle. For spur gears, it is cylindrical; for bevel gears, it is conical

Pitch point

Is the point P which divides the line of centers of a pair of gears into two parts proportional to the number of teeth.

Pitch point

Is the point of tangency on the center line of the pitch circles.

Working Depth (Hw)

The radial distance through which the tooth of one gear actually engages with the tooth of the mating gear. It is equal to the sum of the addenda of the two gears.

Whole Depth (HT)

The total depth of the gear tooth space, measured radially from the addendum circle to the dedendum circle. It is equal to the addendum plus the dedendum.

Circular pitch (Pc)

Is the distance from the center of one tooth the center of the next tooth, measured on the pitch circle. This is, of course, equal to the distance from any point on a tooth to the corresponding point on the next tooth. It is also equal to the tooth thickness plus the space width.

Diametral pitch (Pd)

Is the term ordinarily used to designate the tooth size; it is equal to the number of teeth divided by the diameter of the pitch circle.

Center to Center distance (CC)

Is the distance between the center of the pitch circles of two gears in mesh.

Module (M)

Is used with SI units and is the ratio of the pitch-circle diameter of a gear in millimeters to the number of teeth

Clearance (cl)

The radial distance between the top of a tooth on one gear and the bottom of the mating gear’s tooth space. It prevents interference during meshing

Face

The portion of the tooth surface lying above the pitch surface and between the addendum circle and the pitch circle

Flank

The portion of the tooth surface lying below the pitch surface and between the pitch circle and the dedendum circle.

Acting Flank

The specific part of the flank that is in actual contact with the tooth of the mating gear during operation.

Fillet

The curved transition at the base of the tooth profile that connects the tooth flank to the bottom land. It reduces stress concentration.

Fillet radius, rf

Made equal to the clearance when gear teeth are drawn. However, the actual shape of the fillet curve on a gear will depend on the method used for cutting the teeth.

Tooth thickness (T)

The width of a single tooth measured along the pitch circle

Space width or tooth space (S)

The width of the gap between two adjacent teeth, measured along the pitch circle.

Backlash (BL)

Is the difference between the space width on a gear and tooth thickness on the mating gear measured along the pitch circles.

Bore

The diameter of the hole in a sprocket, gear, bushing, etc.

Top land

The flat surface at the very top of a gear tooth

Bottom land

The flat surface at the very bottom of the gear tooth space (root)

Crowning

A modification that results in the flank of each gear tooth having a slightly outward bulge in its center area.

Gullet

Space between two teeth of a sprocket or gear.

Hub

A shoulder or flange protruding from the side of a sprocket or gear. These provide width to a part, which is used, for mounting the part on a shaft.

Hub Style

Indicates the configuration of the hubs on a sprocket or gear. Type A' indicates that the part has no hub; TypeB' indicates a hub on one side only and Type 'C' indicates a hub on both sides of the part.

Line of Action

The point of contact for any two teeth is always along this line if friction if neglected between the contacting tooth surfaces, then the force which the driving gear exerts on the driven would be along this line is the common tangent to the base circles of two gears in mesh.