Engineering plant facilities 05 mechanics vertical transportation

MECHANICS VERTICAL TRANSPORTATION

L | C | LOGISTICS PLANT MANUFACTURING AND BUILDING FACILITIES EQUIPMENT

Engineering-Book ENGINEERING FUNDAMENTALS AND HOW IT WORKS

September 2014

Expertise in Process Engineering Optimization Solutions & Industrial Engineering Projects Management

Supply Chain Manufacturing & DC Facilities Logistics Operations Planning Management

Vertical Transportation

2,500 lb Capacity

Application

Hydraulic Traditional Traction (geared)

Ed MRL(gearless)

Speed (fpm) 150 200 150-500

Motor size (kW/hp) 40hp/30kW 22hp 8hp

Typical current

values (amp)

Nominal 57 58 12

Starting 114 105 14

Main fuse size (amp) 70@480V 80 15@480V

Main fuse size (amp) 28,000 30,600 8,600

Thermal losses (BTU) 9,000 9,450 3,700

Oil requirement

(gallons)80 4 0

Control space noise level

(dBA)70-80 65-70 50-55


There are four major components to the hydraulic system: a tank (fluid reservoir); a pump powered by an electric motor; a valve between the cylinder and the reservoir; and the cylinder

The pump forces fluid from the tank into the cylinder

As the fluid collects in the cylinder, it pushes the piston up, lifting the elevator car

When the valve is opened, the pressurized fluid will take the path of least resistance and return to the fluid reservoir

When the car approaches the correct floor, the control system sends a signal to the electric motor to gradually shut off the pump and close the valve

With the pump off, there is no more fluid flowing into the cylinder, but the fluid that is already in the cylinder cannot escape (it can't flow backward through the pump, and the valve is still closed)

The piston rests on the fluid, and the car stays where it is


To lower the car, the elevator control system sends a signal to the valve

When the valve opens, the fluid that has collected in the cylinder can flow out into the fluid reservoir

The weight of the car and the cargo pushes down on the piston, which drives the fluid into the reservoir

The car gradually descends

To stop the car at a lower floor, the control system closes the valve again

Traction elevator. Ropes are attached to the elevator car and looped around a hoist machine with deep grooves in its circumference known as a sheave

The sheave grips the hoist ropes, so when the sheave, which is connected to an electric motor, rotates, the ropes move too

When the motor turns one way, the sheave raises the elevator; when the motor turns the other way, the sheave lowers the elevator


In gearless elevators, which have traditionally been used for very tall buildings or to achieve exceptionally fast speeds, the motor rotates the sheaves directly, allowing speeds up to 3,000 fpm (35 mph)

In geared elevators, which have traditionally been used for mid-sized office and residential buildings, the motor turns a gear train that rotates the sheave. Mechanical limitations typically limit the speed to 450 fpm

Traditionally, the sheave, the motor and the control system are all housed in a machine room above the elevator shaft

From the building exterior, the machine room typically appears as a box on the rooftop

Other configurations can be utilized that eliminate the need for the overhead machine room by placing components at or near the first landing-a "basement" configuration-or elsewhere along the shaft/hoist way


The ropes that lift the car are also connected to a counterweight, which hangs on the opposite side of the sheave. The counterweight weighs about the same as the car filled to 40 percent capacity

In other words, when the car is 40 percent full, the counterweight and the car are perfectly balanced. With equal loads on each side of the sheave, it only takes minimal force to tip the balance one-way or the other

Both the elevator car and the counterweight ride on guide rails, which run along the sides of the elevator shaft

The rails keep the car and counterweight from swaying back and forth, and they also work withthe safety system to stop the car in an emergency

The advantages of the traditional traction elevator include:

Fast speeds and efficient performanceQuiet, smooth rideAvailable for high-rise applications

The drawbacks of the traditional traction elevator include:

Higher installation costSignificant structural loads at the top of the hoist wayElevator machine room required


MRL gearless traction machine came about in the mid 1990s, elevator designs began featuring a small permanent-magnet synchronous motor (PMSM) combined with a variable voltage, variable frequency (VVVF) drive

The change reduced the size, weight, heat output and energy consumption of traditional traction systems by up to one-half

Because of the reduced size of the new motor, a machine room above or adjacent to the elevator hoist way was not required

Instead of placing the machine in a separate room, the motor mechanism could be mounted within the hoist way itself


Typically, an AC gearless low-rise elevator with a PMSM has less than a 10 horsepower (hp) motor, compared to motors of up to 40 hp for traction elevators and up to 60 hp for hydraulic motors

The Permanent Magnet Synchronous Motor (PMSM) is an AC synchronous motor whose field excitation is provided by permanent magnets, but has a sinusoidal Back EMF waveform

The PMSM is a close relative of the brushless DC (BLDC) motor. Both motors have a permanent magnet rotor and windings on the stator. However, the PMSM motor is constructed such that the back EMF waveforms of the windings are sinusoidal


The principle difference in controlling these two motors is the kind of drive signals that are supplied to the motor from the inverter

A BLDC motor is controlled with trapezoidal waveforms, while a PMSM motor is controlled using sinusoid waveforms to match the back EMF waveform of each motor’s windings

VFD system a variable frequency drive is a device used in a drive system consisting of the following three main sub-systems: AC motor, main drive controller assembly, and drive operator interface

The AC electric motor used in a VFD system is usually a three-phase induction motor. Some types of single-phase motors can be used, but three-phase motors are usually preferred

Various types of synchronous motors offer advantages in some situations, but three phase induction motors are suitable for most purposes and are generally the most economical motor choice

The new PMSM technology also means energy savings


An escalator is a moving staircase conveyor transport device for carrying people between building floors

Escalators are powered by constant-speed alternating current motors and move at approximately 1–2 feet (0.30–0.61 m) per second. The maximum angle of inclination of an escalator to the horizontal floor level is 30 degrees with a standard rise up to about 60 feet (18 m). Modern escalators have single piece aluminum or steel steps that move on a system of tracks in a continuous loop

Direction of movement (up or down) can be permanently the same, or be controlled by personnel according to the time of day, or automatically be controlled by whoever arrives first, whether at the bottom or at the top (the system is programmed so that the direction is not reversed while a passenger is on the escalator)


The escalator truss is the structural frame of the escalator and consists of three major areas

It is a hollow metal structure that bridges the lower and upper landings. It is composed of two side sections joined together with cross braces across the bottom and just below the top

The ends of the truss are attached to the top and bottom landing platforms via steel or concrete supports

The truss carries all the straight track sections connecting the upper and lower sections

The structural steel truss members are designed to carry the entire load of the escalator equipment and the steel covering without shifting more than specified by the contract requirements


The track system is built into the truss to guide the step chain, which continuously pulls the steps from the bottom platform and back to the top in an endless loop

The relative positions of these tracks cause the steps to form a staircase as they move out from under the comb plateAlong the straight section of the truss, the tracks are at their maximum distance apart

This configuration forces the back of one step to be at a 90-degree angle relative to the step behind it. This right angle bends the steps into a shape resembling a staircase


At the top and bottom of the escalator, the two tracks converge so that the front and back wheels of the steps are almost in a straight line. This causes the stairs to lay in a flat sheet-like arrangement, one after another, so they can easily travel around the bend in the curved section of track

The tracks carry the steps down along the underside of the truss until they reach the bottom landing, where they pass through another curved section of track before exiting the bottom landing. At this point, the tracks separate and the steps once again assume a staircase configuration

This cycle is repeated continually as the steps are pulled from bottom to top and back to the bottom gain


The Drive machine together with the gear reducer provides the torque to drive the step band at a constant speed

The drive machine motor is typically a three-phase AC direct-on-line flange mounted unit. It is either directly or flexibly coupled to the reduction gear. The motor is usually protected by thermal and/or electro-magnetic overload devices as well as thermostats in the motor winding

The main drive machine is located in the upper pit area or in a separate machine room located below the upper section of the escalator

An external drive located in the upper pit area may employ a direct motor to gearbox drive, or a motor to gear reducer with a chain drive

An external drive escalator with the drive unit located within a machine room beneath the upper landing will normally employ a motor/gearbox with a chain drive extending to the upper landing


Machine may be located at the upper landing inside the truss between the step bands or at the top pit, and will employ a motor to gearbox drive with a direct drive axle connection

A separate dual drive machine within the step band is not uncommon with one machine used to directly drive the step chains located a few

feet below the upper incline and one above the lower incline

Internal escalator drive machines may be one, two, or three drive

A dual or three-machine power the main drive shaft or pinion shaft at the upper incline

Some internal drive escalators are equipped with either dual or three drive machines all inside the step band or step-belt


The motor may be directly connected to the gearbox or it may transfer power through a belt drive

The gearbox will have a direct connection to the drive axle

A modular escalator may have a single drive or a multiple drive depending on the overall length of the escalator

Machine and main drive are located within the incline of the truss between the step bands


The soft start controller is a solid state AC drive which controls the speed of AC motors by controlling the frequency and voltage of the power supplied to the motor

It has the following advantages: •It can adjust the motor power to the number of riders using the escalator while maintaining normal speed •It can reduce electricity use by a significant amount•It allows for gradual smooth starting of three-phase squirrel cage motors

It allow precise adjustment of motor starting torque, eliminating mechanical shocks which led to premature bearing wear, shaft and belt breakage, increased maintenance time, and costly production stoppages


The Main Drive Gear or gear reducer assembly may be a single-stage type gear reducer. This is an enclosed, mechanical device that takes the drive motor torque and transmits this torque to the bull gear through a gearbox shaft (pinion) or the main drive chain

The gear reducer assembly contains a steel worm gear that is coupled or directly sleeved onto the motor shaft and it meshes with the pinion (bronze) gear

The step motion is achieved by a direct step assembly connection to the step chains

Two-step chains; one for each side of the escalator are directly coupled to the Main Drive axle, the bull gear shaft, through the step chain sprockets

The step chain form a loop for the length of the truss, from the step chain sprockets at the upper end down to the tension carriage gear or turnaround (depending on the manufacturer) at the lower end or the lower reversing station


The Main Drive Axle is driven by the motor and reducer assembly Sprockets or bull gears. On both ends of the Main Drive Axle transfer power the Step Drive System

These sprockets or bull gears drive two step chains, one each for the right and left sides of the escalator, which are connected at the lower end of the escalator to the step chain sprockets of the Tension Carriage

The Step Chains are endless links connected with link pins to make a complete loop and are attached to an axle on each side of the steps forming a loop which runs for the length of the truss from the upper Main Drive Axle to the lower Tension or Turnaround


The Automatic Lubricator has a gage to show oil reservoir level

The Lubrication Timer can be programmed for any time mode but, is pre-set for a 20 hour cycle

The system dispenses pre-determined amounts of oil to the distribution network which delivers this oil to the bearing points

Note: The Auto Lubrication System does not supply grease to the drive system bearings

Drive bearing lubrication must be done manually. Bearings that need to be manually lubricated are the Main Drive Bearings, the Tension Carriage Bearings, the Motor Bearing, and the Handrail Drive bearings

Additionally, the bearing surface of the Main Drive Shaft Brake, the Step Axle sleeve, the Step Wheel guide-shoe, and the Gear Box are manually lubricated


The Machine Brake is an electromagnetically released, spring-applied, disk that is driven by a spline hub mounted to the extended worm input shaft of the gear-reducer

This type of brake is referred to as a fail-safe brake. When the brake coil is de-energized, springs within the assembly press the armature against the disc, and slowly stop the escalator

The drive shaft brake system , the guide shoe is removed to allow the pawl to drop and engage the ratchet

The Main Drive Shaft Brake It uses a pawl that is welded onto one end of the main drive shaft to engage a ratchet wheel with brake linings on both faces. The brake lining wheel is sandwiched between the handrail 1st drive sprocket and the step chain sprocket

A guide shoe lever is welded onto the opposite end of the main drive shaft. The guide shoe is normally supported by the drive chain and when the chain breaks, the shoe drops and turns the shaft

The drive shaft brake pawl moves into the ratchet wheel and stops the escalator when the guide shoe drops


Hydraulic Dock LevelerSmooth transition - Constant-radius rear hinge, two-point crown control on the front lip hinge, and an optimized lip chamfer provide a smooth transition from the facility floor to the trailer for your operators, forklifts and products

Vacant dock drop-off protection - Exclusive Safe-T-Lip barrier protects against open dock accidents. The Safe-T-Lip barrier can stop a 10,000 lb fork lift traveling at 4 mph from going over the edge of the loading dock

Environmentally friendly - Hydraulic fluid is biodegradable and out performs traditional industrial-grade fluid

Automatic free-fall protection - Dependable hydraulic velocity fuse stops rapid leveler descent within 3" with a heavy load on the platform

Safe-T-Strut maintenance support system protects personnel during clean out and inspection and provides lockout/tag out capability

The unique through-the-lip design keeps the strut in place when the leveler is raised to the highest position or is impacted by lift truck


Hydraulic systems use a incompressible fluid, such as oil or water, to transmit forces from one location to another within the fluid. Most aircraft use hydraulics in the braking systems and landing gear. Pneumatic systems use compressible fluid, such as air, in their operation. Some aircraft utilize pneumatic systems for their brakes, landing gear and movement of flaps

Pascal's law states that when there is an increase in pressure at any point in a confined fluid, there is an equal increase at every other point in the container

A container, as shown below, contains a fluid. There is an increase in pressure as the length of the column of liquid increases, due to the increased mass of the fluid above

For example, in the figure below, P3 would be the highest value of the three pressure readings, because it has the highest level of fluid above it

If the container had an increase in overall pressure, that same added pressure would affect each of the gauges the same (and the liquid throughout)


Pascal's law allows forces to be multiplied. The cylinder on the left shows a cross-section area of 1 square inch, while the cylinder on the right shows a cross-section area of 10 square inches

The cylinder on the left has a weight (force) on 1 pound acting downward on the piston, which lowers the fluid 10 inches

As a result of this force, the piston on the right lifts a 10 pound weight a distance of 1 inch

The 1 pound load on the 1 square inch area causes an increase in pressure on the fluid in the system. This pressure is distributed equally throughout and acts on every square inch of the 10 square inch area of the large piston

As a result, the larger piston lifts up a 10 pound weight. The larger the cross-section area of the second piston, the larger the mechanical advantage, and the more weight it lifts


The formulas that relate to this are shown P1 = P2 Since pressure equals force per unit area, then it follows that F1/A1 = F2/A2

1 pound / 1 square inches = 10 pounds / 10 square inches

Because the volume of fluid pushed down on the left side equals the volume of fluid that is lifted up on the right side, the following formula is also true

V1 = V2

A1 D1 = A2 D2 A = cross sectional area D = the distance moved

A1/A2= D2/D1

This system can be thought of as a simple machine (lever), since force is multiplied

The mechanical advantage can be found by rearranging terms in the above equation (IMA)

Mechanical Advantage(IMA) = D1/D2 = A2/A1

For the sample problem above, the IMA would be 10:1 (10 inches/ 1 inch or 10 square inches / 1 square inch)


A hydraulic pump creates flow in a hydraulic system. It’s commonly mistaken that the pump creates the pressure in a system, but pressure is really just a by product of having flow (usually measured in gallons per minute)

The pump simply generates flow, and the size & speed of the pump determines how much fluid it can move

If a pump is moving fluid through an open system with no resistance, there would be no pressure, but pressure is created when a load is introduced

If you are familiar with electrical systems, there are a lot of parallels to hydraulics. Flow (GPM) would be similar to voltage, while pressure (PSI) would be the equivalent of amperage


In most hydraulic systems, hydraulic cylinders and pistons are connected through valves to a pump supplying high-pressure oil

An electric motor is attached to a hydraulic oil pump

The hydraulic oil pump creates a stream of high-pressure oil, which runs to a valve

The valve lets the operator actuate the hydraulic cylinder to split a log

There is also a tank to hold the hydraulic oil that feeds the pump and usually a filter to keep the oil clean

• 5-horsepower electric motor• two-stage hydraulic oil pump rated at 3 gpm at 2,500 psi• 4-inch-diameter, 24-inch-long hydraulic cylinder• rated splitting force of 20 tons• 3.5-gallon hydraulic oil tank

A two-stage pump contains two pumping sections and an internal pressure-sensing valve that cuts over between the two

One section of the pump generates the maximum gpm flow rate at a lower pressure. It is used, to draw the piston back out of a log after the log has been split


Drawing the piston back into the cylinder takes very little force and it happens quickly, so you want the highest possible flow rate at low pressure

When pushing the piston into a log, however, you want the highest possible pressure in order to generate the maximum splitting force

The flow rate isn't a big concern, so the pump switches to its "high pressure, lower volume" stage to split the log

Pascal's Principle states that when pressure is added to a liquid at rest, there is an identical increase in pressure at all points

Applying this principle to the hydraulic press means that any force that is added to the piston in the smaller cylinder will be transferred to the piston in the larger cylinder, in a proportionally increased level of force. This allows a hydraulic press to produce a great deal of force from the application of a small amount of force to the small piston


Another thing you can determine is the cycle time of the piston. To move a 4-inch-diameter piston 24 inches, you need 3.14 * 22 * 24 = 301 cubic inches of oil

A gallon of oil is about 231 cubic inches, so you have to pump almost 1.5 gallons of oil to move the piston 24 inches in one direction. That's a fair amount of oil to pump -- the maximum flow rate is 11 gallons per minute. It will take 10 or so seconds to draw the piston back after the log is split, and it may take almost 30 seconds to push the piston through a tough log (because the flow rate is lower at high pressures

To determine the multiplication factor, start by looking at the size of the pistons. Assume two pistons working together; one piston on the left is 2 inches in diameter (1-inch radius), while the piston on the right is 6 inches in diameter (3-inch radius)

The area of a pistons is Pi * r2. The area of the left piston is therefore 3.14, while the area of the piston on the right is 28.26. The piston on the right is 9 times larger than the piston on the left

What that means is that any force applied to the left-hand piston will appear 9 times greater on the right-hand piston. So if you apply a 100-pound downward force to the left piston, a 900-pound upward force will appear on the right

The only catch is that you will have to depress the left piston 9 inches to raise the right piston 1 inch


The increase of the force produced by the larger piston is proportionally larger than the force exerted on the small piston. The amount of increase depends on the ratio of the sizes of the pistons

The ratio of the areas of the two pistons is multiplied by the amount of force applied to the small piston to determine the amount of force that the large piston can produce

For example, if the ratio of the sizes of the two pistons is 10, and the amount of force applied to the small piston is 50 Newton, the amount of force that the large piston will produce is 500 Newton


Piston pumps are typically much more complicated and are often available in wither fixed or, commonly, variable displacement configurations and with pressure compensation

These are big words that mean that piston pumps can usually adapt to the system pressure, providing maximum efficiency and flexibility

They are often used in “closed center” systems where the pump displacement varies to meet the needs of the work being done

Piston pumps use a “swashplate” to move the pistons and the angle of the swashplate & bore of the pistons determines the displacement. Pressure compensation regulates outputs in response to variations in the system

Piston pumps are typically the most efficient type of hydraulic pump


A 4-inch piston has an area of 12.56 square inches. If the axial piston pump generates a maximum pressure of 3,000 pounds per square inch (psi), the total pressure available is 37,680 pounds

The basic idea behind any hydraulic system is very simple: Force that is applied at one point is transmitted to another point using an incompressible fluid

The fluid is almost always an oil of some sort. The force is almost always multiplied in the process


They have no metal-to-metal contact & self-compensate for wear, since the vanes self extent to fit the housing. They are also very effective in fluid transfer, thanks to excellent suction characteristics

Vane pumps use a series of “fins” or vanes to create flow

The fluid is swept around a crescent-shaped housing cavity and flow is created by the difference in volume by the variation in the housing

Vane pumps are typically smoother & quieter than gear pumps, so they commonly work well in industrial systems and hydraulic units that will be used indoors. They have no metal-to-metal contact & self-compensate for wear, since the vanes self extent to fit the housing. They are also very effective in fluid transfer, thanks to excellent suction characteristics


Calculating Hydraulic Cylinder TonnageMeasure the diameter of the piston of the hydraulic cylinder

Calculate the cross-sectional area of the piston by squaring the diameter, multiplying the result by pi (3.14), then divide this result by 4. For example, for a piston with a 5 inch diameter, the cross sectional area is (5” * 5” * 3.14)/4 = 19.625 sq. inches

Calculate the cylinder tonnage by multiplying the cross sectional area as calculated above by the pressure capacity of the hydraulic pump, as listed in the pump specifications

For example, using the example cylinder above and a 1,000 psi pump, the cylinder capacity is (19.625 sq. inches) *(1,000 psi) = 19,625 lbs

To convert from pounds to tons, divide this result by 2,000 to get 9.8 tons

Thank You

L | C | LOGISTICS PLANT MANUFACTURING AND BUILDING FACILITIES EQUIPMENT

Engineering-Book

ENGINEERING FUNDAMENTALS AND HOW IT WORKS

MECHANICS VERTICAL TRANSPORTATION

Engineering plant facilities 05 mechanics vertical transportation

Engineering

Transcript of Engineering plant facilities 05 mechanics vertical transportation