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E-Mail: adamnik@liberator.lib.uts.edu.au



                           Using HydraCyl version 1.3x

                                  E X A M P L E


Here is an example of a hypothetical design to illustrate the step by
step procedure involved in HydraCyl.

Design specifications are:

*     Cylinder Duty                      Heavy

*     Cylinder Bore Dimension             2   inches

*     Cylinder Rod Dimension              1   inch

*     Cylinder Stroke                    34   inches

*     System Flow                        25   litres/min

*     Pressure                           60   bar

*     Attached Mass                    2300   kg

*     Cylinder - Valve distance         150   inches

(The length of pipes between the Cylinder's ports and the Solenoid
valve)

*     Cylinder Mounting Type             Intermediate trunnion

*     Mounting Orientation               The applied mass permanently
                                         attached to the piston rod
                                         stud and Cylinder rod
                                         extends and retracts.

*     Spacial orientation                35   deg

*     Coefficient of Friction            0.15

*     Hydraulic Line Dimensions          6   mm (outside diameter)
                                         'L'  series


1.      Run HC.EXE
2.      Choose 'OK' on form 'About'
3.      Choose 'Analysis'
4.      Choose 'Perform Analysis'

You will get a message: 'Cylinder Dimensions must be specified'

5.      Choose 'OK'

Let's say you want a heavy duty 2"/1" cylinder

6.      Click on '( ) Heavy' in the 'Cylinder's Duty' box
7.      Click on Cylinder Bore Diameter 2.00
8.      Click on Cylinder Rod Diameter 1.00
9.      Click on 'OK'
10.     Choose 'Analysis'
11.     Choose 'Perform Analysis'

You will get a message: 'Cylinder Operating Parameters must be specified'

12.     Choose 'OK'

Let's say the stroke of your cylinder is 34 inches, firstly you need
to have the correct units.

13.     Choose 'Change Units'
14.     Click on '( ) inch' in the 'Stroke' box
        (this will be the default unit for stroke until you 
        change it back to 'mm')
15.     Click 'OK'

Now you can enter the stroke.

16.     Click in '[_     ] inch' under the 'Stroke' heading
17.     Type 43  (OOPS my typing mistake, should be 34)
18.     Click on 'Clear Values'
19.     Click on 'Stroke'
20.     Type 34 (correct value)

Let's say the system flow is 25 lit/min

21.     Click in '[_     ] lit/min' next to the 'System Flow' heading
22.     Type 25

Let's say the Pressure is 60 bar

23.     Click in '[_     ] bar' next to 'Pressure'

        (if it is required change units to 'bar' in the similar manner as
         stroke.)

24.     Type 60

Let's say the attached mass is 2300 kg

25.     Click in '[_     ] kg' next to 'Applied Mass'
26.     Type 2300

Let's say the pipeline length between Cylinder's ports and solenoid
valve is 150 inches.

27.     Click in '[_     ] inch' next to 'Cyl-Valve distance'
28.     Type 150
29.     Click 'OK'
30.     Choose 'Analysis'
31.     Choose 'Perform Analysis'

You will get a message: 'Cylinder Mounting Type must be specified'

32.     Choose 'OK'

Let's say the cylinder mounting type is 'Intermediate trunnion'

33.     Click on 'View Basic Mount Types (a - p)'
34.     High resolution picture is shown of all possible mounting
        types. Look for Intermediate trunnion. It is marked by 'b'
35.     Press any key to get out of diagram.
36.     Click on 'b0'
37.     Click on "View Detail of Selected Mount"

High resolution picture is shown of 'b0' of Intermediate trunnion
mounting type, N.F.P.A. Style MT4.

38.     Press any key to get out of diagram.
39.     Click on 'b0' (to ensure chosen mounting type)
40.     Click 'OK'
41.     Choose 'Analysis'
42.     Choose 'Perform Analysis'

You will get a message: 'Cylinder Mounting Orientation Must be specified'

43.     Choose 'OK'

Let's say a mass of 2300kg is permanently attached (cylinder rod
extending and retracting) to cylinder. Cylinder is mounted under 35
degrees slope, and mass is attached to Piston Rod Stud. Friction
coefficient is 0.15.

44.     Click on 'View Orientation Diagrams'

High resolution picture is shown of all mounting orientation types.
Look for above description. It is marked as '3'

45.     Press any key to get out of diagram.
46.     Click on '3'

47.     Click in '[_     ]' next to 'Angle between OX and OZ axis'
48.     Type 35

49.     Click in '[_     ] kg' next to 'Coefficient of friction'
50.     Type 0.15
51.     Click 'OK'

52.     Choose 'Analysis'
53.     Choose 'Perform Analysis'

You will get a message: Hydraulic Line Dimensions must be specified

54.     Choose 'OK'

Let's say that Hydraulic line between Cylinder port's and Solenoid
valve are 6mm outside diameter and 'L' series. Initially "inch" Pipe
(Tubes) form is shown.

55.     Click on Pipe/Tube Standard (Top right hand corner of the
        form)
56.     Choose 'Metric/Germany'
57.     Click on Outside Diameter Size 6
58.     Click on Series L
59.     Click on 'OK'
60.     Choose 'Analysis'
61.     Choose 'Perform Analysis'

You will get a message: 'Calculating...'

(this means that all relevant data has been entered and now you will
see the results of HydraCyl's analysis)

You get a Warning:  SUPPLY PRESSURE  Required pressure for
                    Cylinder's extending is low, consult Page 5.

62.     Observe top left corner of the screen. There is title:
        Cylinder Data - Page 4 of 8.

63.     Choose 'Page Down'
64.     Observe Min.Total Pressure Rod Extending = 87.00 bar

Now we will make changes to our specifications to try to overcome
this design problem.
                                      
65.     Choose 'Cylinder' (on top left hand side of screen)
66.     Choose 'Operating Parameters'
67.     Choose 'Clear Values' button (click it)
68.     Choose 'Pressure' button (click it)
69.     Change 'Supply pressure' to 90 bar.
70.     Click 'OK'
71.     Choose 'Analysis'
72.     Choose 'Perform Analysis'
73.     Choose 'OK'

You will get a Warning: ROD BUCKLING Rod is buckling. Select larger
                        cylinder or use other engineering methods.
                        Consult pages 2 and 3.

74.     Observe top left corner of the screen. There is title:
        Cylinder Data - Page 4 of 8.
75.     Choose 'Page Up'
76.     Browse pages until you get page 2 on the screen.
77.     Play between pages 2 and 3 and observe values of:

        (page 2) Extending Force =  1824 daN
        (page 3) Column Strength  =  585 daN

Obviously that actual extending (static) force is almost 4 times
higher than Piston Column strength. Now we will make some changes to
our specifications to try to overcome this design problem.

78.     Choose 'Cylinder' (on top left hand side of screen)
79.     Choose 'Dimensions'
80.     Choose 'Catalogue-Imperial'
81.     Click on '( ) Heavy' in the 'Cylinder's Duty' box
82.     Click on Cylinder Bore Diameter 2.00
83.     Click on Cylinder Rod diameter 1.375".

We have just changed cylinder rod diameter from 1" to 1.375" to try
to eliminate buckling effects.

84.     Click 'OK'
85.     Choose 'Analysis'
86.     Choose 'Perform Analysis'
87.     Wait a few seconds

At last NO Warnings. That means all parameters are acceptable and
properly entered. You have selected a suitable cylinder.  At this
stage it is common to check fluid flow velocity through pipe (tube).

88.     Browse pages until you get 'Cylinder Data - Page 6 of 8'
89.     Observe maximum fluid flow velocity.

It is common practice, that in those lines carrying 35 to 150 bar
(approx. 500 to 2000 PSI), flow velocity should be kept to 4.5 to 6
m/sec (approx. 15 to 20 feet/sec), and for 200 to 350 (approx. 3000
to 5000 PSI) bar flow velocity may be allowed up to 9 m/sec (approx.
30 feet/sec).

90.     Choose 'Cylinder' (on top left hand side of screen)
91.     Choose 'Hydraulics Pipe (Tube)'
92.     Choose 'Metric/Germany Standard'

We need to make assumption to drop in above common limits of pressure
and flow velocity.  Let's assume 15 L pipe.

93.     Click on Outside Diameter 15.
94.     Choose 'OK'
95.     Choose 'Analysis'
96.     Choose 'Perform Analysis'

Most of flow velocities for different cylinder movement are at
acceptable level. You may try to experiment with various Pipes
(Tubes).  If something goes wrong you will be warned on time.  During
the experiment by repeating steps 93 to 96 you may wish to observe
page 5 of 8 and influence of chosen pipe tubes on 4 main parameters
of:

Min.Travel Distance Rod Extending
Min.Travel Distance Rod Retracting    
Min.Total Pressure Rod Extending
Min.Total Pressure Rod Retracting

More about it later.

Let's look at the analysis' results.  Use 'Page Up' and 'Page Down'
to browse the inputs and results on the 'Cylinder Data' form, they
are as follows:

                                                11-Feb-1997   7:48 am
 + Cylinder Data - Page 1 of 8 -----------------------------------------+
 |                                                                      | 
 | Cylinder Dimensions:                                                 | 
 |          Bore Diameter       2.00  inch    (This is the cylinder     |
 |           Rod Diameter       1.375 inch       size you have now      |
 |                 Stroke      34.00  inch       selected for your      |
 |                                               application)           |
 | Hydr.Line Dimensions:                                                | 
 |   Pipe (Tube) Diameter       15      L                               | 
 |     Cyl-Valve Distance     150.00  inch                              | 
 |                                                                      | 
 | Mounting:                                                            | 
 |        Duty      Heavy                                               | 
 |        Type  b0  MT4: Intermediate trunnion                          | 
 |                                                                      | 
 | Orientation  3   Fixed Cylinder Body. Piston Rod retracting and      | 
 |                  extending. Load attached to Piston Rod Stud.        | 
 |                                                                      | 
 +----------------------------------------------------------------------+ 
                                                  11-Feb-1997   7:48 am
 + Cylinder Data - Page 2 of 8 -----------------------------------------+ 
 |                                                                      | 
 |       Cylinder's Slope      35.00  deg                               | 
 |   Friction Coefficient       0.15                                    | 
 |                                                                      | 
 | Operating Parameters:                                                | 
 |                                                                      | 
 |            System Flow      25.00  lit/min                           | 
 |        Extending Speed     205.58  mm/sec                            | 
 |         Extending Time       4.20  sec                               | 
 |       Retracting Speed     389.83  mm/sec                            | 
 |        Retracting Time       2.22  sec                               | 
 |                                                                      | 
 |        Supply Pressure      90.00  bar                               | 
 |    Max Pressure Rating     138.00  bar                               | 
 |                                                                      | 
 |        Extending Force    1824.00  daN                               | 
 |       Retracting Force     962.00  daN                               | 
 +----------------------------------------------------------------------+ 
                                                  11-Feb-1997   7:48 am
 + Cylinder Data - Page 3 of 8 -----------------------------------------+ 
 |                                                                      | 
 |        Column Strength    2091.00  daN                               | 
 |           Applied Mass    2300.00  kg                                | 
 |                                                                      | 
 | Other Analysis Results:                                              | 
 |                                                                      | 
 |              Stop Tube       2.00  inch                              | 
 |                                                                      | 
 |  Extending Return Flow      13.18  lit/min                           | 
 | Retracting Return Flow      47.41  lit/min                           | 
 |                                                                      | 
 |           System Power       3.75  KW                                | 
 |                                                                      | 
 |              Bore Area       3.14  sq.inch                           | 
 |               Rod Area       1.48  sq.inch                           | 
 |           Annulus Area       1.66  sq.inch                           | 
 |                                                                      | 
 +----------------------------------------------------------------------+
                                                   11-Feb-1997   7:48 am
 + Cylinder Data - Page 4 of 8 -----------------------------------------+ 
 |                                                                      | 
 | Displacement Volume:                                                 | 
 |                                                                      | 
 |          Cylinder Head     0.9230  litre                             | 
 |           Cylinder Cap     1.7504  litre                             | 
 |        Total Reservoir     0.8273  litre                             | 
 |         Total Cylinder     2.6734  litre                             | 
 |                                                                      | 
 |                                                                      | 
 |                                                                      | 
 |                                                                      | 
 | Warnings:                                                            | 
 |                         No Warnings.                                 | 
 |                                                                      | 
 |                                                                      | 
 |                                                                      | 
 |                                                                      | 
 +----------------------------------------------------------------------+ 
                                                  11-Feb-1997   7:48 am
 + Cylinder Data - Page 5 of 8 -----------------------------------------+ 
 |                                                                      | 
 | Undamped Natural Frequency, Minimum Acceleration/Deceleration Time,  | 
 | Distance and Pressure.                                               | 
 |                                                                      | 
 |                                                                      | 
 | Natural Frequency Rod Extending            8.0    Hz                 | 
 | Natural Frequency Rod Retracting           8.0    Hz                 | 
 |                                                                      | 
 | Minimum Ramp Time Rod Extending            0.48   sec                | 
 | Minimum Ramp Time Rod Retracting           0.48   sec                | 
 |                                                                      | 
 | Min.Travel Distance Rod Extending          1.9    inch               | 
 | Min.Travel Distance Rod Retracting         3.7    inch               | 
 |                                                                      | 
 | Min.Total Pressure Rod Extending          86.00   bar                | 
 | Min.Total Pressure Rod Retracting        -38.00   bar                | 
 |                                                                      | 
 +----------------------------------------------------------------------+ 
                                                  11-Feb-1997   7:48 am
 + Cylinder Data - Page 6 of 8 -----------------------------------------+ 
 |                                                                      | 
 | Fluid Flow Velocity Through Pipe (Tube)                              | 
 |                                                                      | 
 |                                                                      | 
 |    Cylinder Rod Extending                                            | 
 |                                                                      | 
 |        Cap End Pipe                        4.38        m/sec         | 
 |                                                                      | 
 |        Head End Pipe                       2.31        m/sec         | 
 |                                                                      | 
 |                                                                      | 
 |    Cylinder Rod Retracting                                           | 
 |                                                                      | 
 |        Cap End Pipe                        8.31        m/sec         | 
 |                                                                      | 
 |        Head End Pipe                       4.38        m/sec         | 
 |                                                                      | 
 +----------------------------------------------------------------------+
                                                   11-Feb-1997   7:48 am
 + Cylinder Data - Page 7 of 8 -----------------------------------------+ 
 |                                                                      | 
 |  Minimum Pressure To Decelerate A Cylinder In A Specified Distance   | 
 |  When System Pressure Applies To Cylinder's Ports:                   | 
 |                                                                      | 
 |        Braking Distance     Head End Pressure    Cap End Pressure    | 
 |               inch                 bar                  bar          | 
 |                0.50                  53.00               163.00      | 
 |                0.75                  41.00               141.00      | 
 |                1.00                  35.00               129.00      | 
 |                1.25                  31.00               122.00      | 
 |                1.50                  29.00               118.00      | 
 |                1.75                  27.00               114.00      | 
 |                2.00                  26.00               112.00      | 
 |                                                                      | 
 |         +-----------------------------------------------------+      | 
 |         |          Braking Diagram - High Resolution          |      | 
 |         +-----------------------------------------------------+      | 
 +----------------------------------------------------------------------+ 
                                                   11-Feb-1997   7:48 am
 + Cylinder Data - Page 8 of 8 -----------------------------------------+ 
 |                                                                      | 
 |  Minimum Pressure To Decelerate A Cylinder In A Specified Distance   | 
 |  When System Pressure Doesn't Apply To Cylinder's Ports:             | 
 |                                                                      | 
 |        Braking Distance     Head End Pressure    Cap End Pressure    | 
 |                inch                bar                 bar           | 
 |                                                                      | 
 |                0.50                   0.00               116.00      | 
 |                0.75                   0.00                93.00      | 
 |                1.00                   0.00                82.00      | 
 |                1.25                   0.00                75.00      | 
 |                1.50                   0.00                70.00      | 
 |                1.75                   0.00                67.00      | 
 |                2.00                   0.00                64.00      | 
 |                                                                      | 
 |                                                                      | 
 |                                                                      | 
 +----------------------------------------------------------------------+ 


Conclusions:
============

Stop tube of 2 inch as shown on page 3 of 8 must be mounted in your cylinder.

Although pump (System) delivered flow is only 25 lit/min, command
hydraulics block (solenoid valve and other components) should be
dimensioned on nominal value of flow 47.41 lit/min. If you neglect
this data you could not expect to get all speeds in your application.

When Cylinder's rod is retracted on that side you need 0.923 litre of
oil. When Cylinder's rod is extended on that side you need 1.7504
litre of oil. For proper work of cylinder you need only 0.8273 litre
of oil in your power unit (reservoir). That is total value of oil
that is required by cylinder for proper 'breathing'. Total Cylinder
2.6734 litre indicates oil volume requirement for cylinder 1 full
cycle.

If you are in need to implement proportional device, you should
consider ramp time longer than 0.48 sec for cylinder extending and/or
retracting. Under those conditions, the attached load requires at

least 1.9 (respectively 3.7) inch travel distance for its
acceleration/deceleration from zero to maximum (maximum to zero)
corresponding speed.

On the page 5, you could read:

     Min.Total Pressure Rod Retracting = -38.00   bar

Due to fact that negative absolute pressure is nonexistent one (in
the nature), the sign '-' is only pointing to absolute pressure of 36
bar at the cylinder cap end port generated by attached mass and
friction forces only. In other words, you should have the relief
valve in that line during acceleration and deceleration and adjust
its value to 36 bar. In such way you will be able to control
acceleration and deceleration of attached mass during rod retracting.


Stroke-Braking Pressure Chart (Deceleration Device)
---------------------------------------------------

Two pages are related to Minimum Pressure To Decelerate A Cylinder In
A Specified Distance. They are:

page 7 of 8 - System Pressure applies to cylinder's ports.
page 8 of 8 - System Pressure does not apply to cylinder's ports.

By observing the chart (page 7 of 8, shown on Figure 1) you are able
to rapidly determine correlation between generated braking pressure
and accompanied braking stroke.

(please run program EXAMPPCX.EXE to see a picture - Figure 1)

Due to fact that braking pressure at Cylinder's Head End is under 138
bar (maximal pressure rating for chosen cylinder), that side of
Cylinder should be supplied with standard cushion. On the other side,
Cap End should be supplied with standard cushion only if its length
is slightly over 3/4 inch (red and green lines intersection). For
that length, the maximum pressure rating (red line) and generated
braking pressure (green line) are at the same value.

You can easily obtain information on standard cushion length (braking
stroke) and maximal pressure rating from your favourite supplier of
cylinders. Just enter those data on the chart and you will get
information on what would happen in the cylinder. Generally, for any
value of braking stroke between 1/2 inch and 2 inch you are able to
determine actual braking pressure.

Information on page 8 of 8 is particularly useful when you
considering free fall movement.


Fluid Flow Velocity Through Pipe (Tube)
---------------------------------------

You may recognise different results obtained from HydraCyl when only
one design parameter is changing.  In this case it is Pipe (Tube)
dimension which is incorporated into your application.  For the sake
of brevity, let's analyse the influence of the whole range of
available pipes (tubes) on the market on:

Minimum Travel Distance
    a. Rod Extending                           inch
    b. Rod Retracting                          inch

Minimum Total Pressure
    c. Rod Extending                           bar
    d. Rod Retracting                          bar

Cylinder Rod Extending
    e. Cap End Pipe                            metre/sec
    f. Head End Pipe                           metre/sec

Cylinder Rod Retracting
    g. Cap End Pipe                            metre/sec
    h. Head End Pipe                           metre/sec

HydraCyl gives the following results:

Pipe    a    b    c      d     e       f      g      h

 6 L   1.6  3.0  87.0  -36.0  33.16  17.49  62.88  33.16
 8 L   1.6  3.1  87.0  -37.0  14.74   7.77  27.94  14.74
10 L   1.7  3.2  87.0  -37.0  10.83   5.81  20.53  10.83
12 L   1.8  3.4  86.0  -37.0   6.55   3.45  12.42   6.55
15 L   1.9  3.7  86.0  -38.0   4.38   2.31   8.31   4.38
18 L   2.2  4.2  85.0  -39.0   2.36   1.24   4.47   2.36
22 L   2.5  4.7  85.0  -40.0   1.64   0.86   3.10   1.64
28 L   3.0  5.7  84.0  -41.0   0.92   0.49   1.75   0.92
35 L   3.6  6.9  84.0  -42.0   0.55   0.29   1.05   0.55
42 L   4.1  7.7  83.0  -43.0   0.41   0.22   0.78   0.41


From this table the following might be observed:

-     Pipe (Tube) diameters has enormous influence in overall
      cylinder behaviour, ie. cylinder movement is more controllable
      (shortest acceleration/deceleration distances) when
      incorporated pipes in system have smaller diameter. In
      engineering therms, system with bigger pipes is more inertial.

-     More energy (pressure) is required for previous point as pipe
      diameter is smaller.



The rule of thumb:      Use pressure/fluid velocity ratio explained
                        in step 89 of this example as good pointer
                        for choosing 'optimum' pipe diameters.



We will leave for you to made simmilar analysis and determine
influence of pipes' length on overall cylinder - attached masss
(system) behaviour.

                               --  end of file --
