Engineering plant facilities 05 mechanics vertical transportation

L | C | LOGISTICS
PLANT MANUFACTURING AND BUILDING FACILITIES EQUIPMENT
Engineering-Book
ENGINEERING FUNDAMENTALS AND HOW IT WORKS
MECHANICS VERTICAL TRANSPORTATION
September 2014
Supply Chain Manufacturing & DC Facilities Logistics Operations Planning Management
Expertise in Process Engineering Optimization Solutions & Industrial Engineering Projects 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 with
the safety system to stop the car in an emergency
The advantages of the traditional traction elevator
include:
Fast speeds and efficient performance
Quiet, smooth ride
Available for high-rise applications
The drawbacks of the traditional traction elevator
include:
Higher installation cost
Significant structural loads at the top of the hoist
way
Elevator 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 plate
Along 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

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

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 Leveler
Smooth 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
Mechanical Advantage(IMA) = D1/D2 = A2/A1
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)
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
• 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
There is also a tank to hold the hydraulic oil that feeds
the pump and usually a filter to keep the oil clean
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

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
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

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
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 Tonnage
Measure 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

L | C | LOGISTICS
PLANT MANUFACTURING AND BUILDING FACILITIES EQUIPMENT
Engineering-Book
ENGINEERING FUNDAMENTALS AND HOW IT WORKS
MECHANICS VERTICAL TRANSPORTATION
Thank You

Engineering plant facilities 05 mechanics vertical transportation

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