US2469011A - Train performance calculator and recorder - Google Patents

Description

May 3, 1949. s. v. SMITH 2,469,011

TRAIN PERFORMANCE CALCULATOR AND RECORDER Filed June 5, 1946 4 Sheets-Sheet l N N cw Q S. V. SMITH TRAIN PERFORMANCE CALCULATOR AND RECORDER Filed June 5, 1946 May 3, 1949.

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TRAIN PERFORMANCE CALCULATOR AND RECORDER Filed June 5, 1946 4 Sheets-Sheet 4 ADJUSTMENTJl/DE WI'INESSES INVENTOR- e KS1]? 'k W J AS] 12001 if A TTORNEYS.

Patented May 3, 1949 TRAIN PERFORMANCE CALCULATOR AND RECORDER Spencer V. Smith, Wayne, Pa., assignor to The Pennsylvania Railroad Company, Philadelphia, Pa., a corporation of Pennsylvania Application June 5, 1946, Serial No. 674,540

1 Claim. 1

For the efficient operation of railway systems and in the design and manufacture of railroad equipment, performance data is required for the various types of equipment used. Such data should cover not only the desired performance characteristics of a given locomotive for a given load but should also indicate performance with a given load over that pait of the railway system under consideration, taking into account the various operating restrictions applicable. For many years determinations of such data have been laboriously calculated by solving a large number of separate mathematical problems in a step by step series of calculations. For instance, where the available tractive efiort values for a given locomotive are known, together with the train resistance values of the particular train, it is possible to calculate theoretical train performance at any given point along a known track profile. If a sufficiently large number of such points are plotted on a graph, a train performance curve is obtained. This method of calculation is not only inefiicient and time consuming but is also subject to arithmetical errors. Moreover, due to the complexity of the problems involved, certain desirable values are not made readily available.

It is therefore one object of the present invention to provide a device for continuously calculating and recording train performance data.

It is a further object of the present invention to provide a process and apparatus for simulating desired conditions of train operation, and for recording values derived from such simulation as permanent records of train performance.

For purposes of clarity the following definitions are included covering some of the terms used in the present specification:

Tractive effort is the force, expressed in pounds, developed at the rim of the driving wheels of a locomotive, or other type of motive power, which tends to advance the motion of a train.

Braking efiort, also expressed in pounds, is a counter force which tends to retard the motion of a train and bring it to rest.

Train resistance is a variable force at various speeds. It is expressed in pounds, and represents the force which is required to keep a train moving at constant speed on a level tangent track.

Grade resistance, expressed in pounds and equal to twenty pounds per ton for each one per cent of grade, is a force which tends to retard the motion of a train on ascendin grades and to advance the motion of a train on descending grades.

Net tractive effort on level tangent track, usually expressed in pounds per ton, is equal to the tractive effort minus the train resistance, divided by the total weight of th train, in tons.

Rate of acceleration, expressed in miles per hour per second, is the rate of increase in speed of the train.

It is well known in the railroad art that different types of railway locomotives have different tractive effort characteristics. There are, however, certain assumptions which are commonly made whichare applicable to all types. Thus it is common practice to assume that one hundred pounds per ton of net tractive eiiort on a level tangent track can produce a rate of acceleration of one mile per hour per second. Similarly, it is common practice to assume that twenty pounds per ton of grade resistance can increase or decrease the rate of acceleration by 0.2 mile per hour per second, depending upon whether the train is descending or ascending the grade. From tractive effort data developed by tests of the type of locomotive under consideration, and from train resistance values calculated for the particular train, it is possible to prepare a curve showing the relation of net tractive eiiort on a level tangent track to speed. By converting net tractive effort values to acceleration values it is also possible to prepare a curve showing the relation between acceleration in miles per hour per second to speed in miles per hour. Such a curve is shown in Fig. 1 of the drawings described below, and represents the initial data which is used in the operation of the device of the present invention. By properly adjusting resistance I, the voltage gradient across slide wire 2 is made to correspond with the curve of Fig. 1. In addition to the acceleration-speed chart of Fig. 1 a chart is also prepared showing speed restrictions, grades and braking requirements for that section of the railway system over which it is desired to simulate operation and for which performance data is desired. These conditions of operation are plotted on a speed-distance chart as shown in. Fig. 2 of the drawings.

The construction and operation of the calculating and recording device of the present invention will be apparent from the following description of the drawings.

Fig. 1 is a chart on which are plotted calculated values showing the relationship between acceleration and speed for a given locomotive drawing a given train.

Fi 2 is a speed-distance chart on which are plotted operating speed restrictions, grades and braking requirements for a given section of a railway system.

Fig. 3 is a diagrammatic showing of the operative elements of the device of the present invention and the electrical circuits by which they are interconnected.

Fig. 4 is a diagrammatic view of the operating details of the air conditioning switch mechanism ii of Fig. 3.

Fig. 5 is a diagrammatic view of the operating details of the time indicator mechanism 3| of Fig. 3.

Fig. 6 is a diagrammatic view of the operating details of the make-and-break mechanism forming a part of speed integrator 22 of Fig. 3.

Referrim now to Fig. 3 of the drawings, a net tractive effort adjustment unit is shown at A comprising a series of manually adjustable resistances I electrically interconnected in series and having individual leads connected to the contacts of a tapped slide wire 2 having a movable contact arm 3 which may be moved to any position from to 100 miles per hour along slide wire 2. Adjustable resistances I are provided to cover a speed range from zero to one hundred miles per hour at intervals of one adjustable resistance for every additional five miles per hour of speed. For the sake of clarity individual resistances and slide wire contacts in the middle of the speed range have not been shown except as shown by the broken lines which are intended to indicate that such resistances and slide wire contacts would be included to cover the entire speed range. An external voltage source which is shown in the form of battery 4 is provided for use in conjunction with resistances I and movable arm 3 as hereinafter described. It will be apparent that an electric transformer or other voltage source may be used in place of the battery 4. Likewise electric transformers may be used in place of the batteries later discussed supplying external voltages to the various p0 tentiometers shown in Fig. 3.

One side of battery 4 is connected through resistance I and slide wire 2, in multiple, movable arm 3 and switch to acceleration-time recorder unit B at galvanometer 6. The other side of battery 4 is connected to unit B at potentiometer I through potentiometers 39, 3'1 and. 35. Unit B includes a galvanometer 5; a potentiometer 7 having an external voltage source 8; a synchronous motor 9; a potentiometer I0 having an external voltage source ii; a control device I2 for measuring voltage at galvanometer 6 and initiating balancing movements of the arm of potentiometer I and an acceleration integrator i3 for operation of the movable arm of potentiometer I!) in response to integrated values derived from the balancing movements of the movable arm of potentiometer 1. Unit B also includes recording drum I4 which is driven by the synchronous motor 9, and an indicating and recording element I5 which is actuated when the position of the movable arm of potentiometer 7 is changed through the action of control device !2. Control device I2 is mechanically connected to galvanometer 6 and also to the movable arm of potentiometer I. This mechanical connection and the mechanism and operation of control device I2 may be of the type shown in U. S. Patent 1,935,732 wherein feelers are provided for determining departures from a predetermined normal position of the needle of galvanometer B. As shown in detail in the above patent, additional mechanism actuated by synchronous motor 0 is provided for changing the position of the movable arm of potentiometer in response to the departures detected by said feelers so as to bring about a return of the galvanometer needle to its normal position through the voltage change thus produced. This measuring and balancing operation occurs intermittently (about twenty-five times per minute), and during the intervals between measurements the needle of galvanometer 6 is free to respond to the voltage diiference between the value impressed on it from outside unit B and that derived from voltage source 8.

The voltage impressed on the galvanometer 5 from the battery 4 and connected circuits is proportional to the available acceleration under the conditions of speed, grade and operating conditions applicable at any given time. Since this acceleration voltage will be a variable, the position of the movable arm of potentiometer 1 will be indicative of the instantaneous acceleration values. By centering the movable arm of potentiometer I at zero, it is possible to obtain positions of the arm corresponding to positive or negative acceleration (deceleration). This changing position of the movable arm of potentiometer I is recorded by the recording pen I5 on a chart (not shown) carried by the movable recording drum I4. The synchronous motor 9 rotates the recording drum I4 at a constant rate proportional to time, and consequently the trace formed by the recording pen I5 gives a curve showing acceleration at any time.

Acceleration integrator I3 is provided to integrate acceleration values represented by the position of the movable arm of potentiometer I in such a way as to produce a movement of the movable arm of potentiometer II] proportional to the integrated value. Acceleration integrator i3 may be of the type described in U. S. Patent 2,399,790 and operates through gears driven by motor 8 and the action of a notched disk in conjunction with a ratchet and pawl mechanism to integrate with respect to time the magnitudes of the voltages being measured as represented by the position of the arm of potentiometer I. Since the integration is with respect to time, the integrated value is an indication of speed and therefore the voltage derived from the external voltage supply II through potentiometer I0 and applied to the galvanometer I! and potentiometer I5 of speed-time recorder C is proportional to speed.

Speed-time recorder C in addition to potentiometer i6 and its external voltage source [8 includes a galvanometer IT, a synchronous motor I9, a potentiometer 20 having an external voltage source 2I, a speed integrator 22, a recording drum 23 adapted to be rotated by a synchronous motor 29, an indicating and recording element 24 responsive to movements of the arm of potentiometer I6 and a control device 25 which is mechanically connected to the arms of potentiometers l6 and 20 and the movable arm 3 by means of control shaft 44. Control device 25 is similar in construction and operation to control device I2 of unit B and operates through the action of a feeler mechanism in a similar way to produce balancing movements of the arm of potentiometer I6 which will maintain the needle of galvanometer I! at a predetermined neutral position. The position for balance of the arm of potentiometer i6 is an indication of speed since the variable voltage coming from potentiometer I0 is proportional to speed, as mentioned above. As in the case of recording drum l4, recording drum 23 is rotated at a uniform rate proportional to time. This rotation is carried out through the action of synchronous motor l9. Consequently, movements of the recording element 24 on a chart (not shown) attached to recording drum 23 result in a trace showing speed at any time.

By a mechanical connection through shaft M (shown diagrammatically in Fig. 3) the position of movable arm 3 is changed in response to changes in the position of the arm of potentiometer l6 and this arrangement is such as to cause the movable arm 3 to move to progressively higher speed positions along the tapped slide wire 2 as the speed values at potentiometer it increase. When the speed decreases arm 3 moves to lower speed positions. The effect of this following action on the part of arm 3 on the operation of the device as a whole is discussed at a later point in this specification.

A mechanical connection through shaft 44 is also provided for moving the arm of potentiometer in response to balancing movements of the arm of potentiometer It. Since these adjustment reflect changes in speed the voltage derived from external source 2i through potentiometer 20 will be proportional to speed. These voltages are impressed on galvanometer 255 and potentiometer 2'! which form a part of Speed- Distance recorder unit D. Unit D also includes 7 an external voltage source 28 for potentiometer 21, a synchronous motor 29, a control device 30, a time indicator 3|, a recording chart drive motor 32, a chart drum 33 and indicating and recording elements 34 and 4-3. is similar in construction and operation to control devices l2 and 25 and by means of a similar feeler mechanism intermittently measures departures of the needle of galvanometer 26 from a predetermined normal position and brings about a balancing movement of the arm of potentiometer 2! such as to return the needle of galvanometer 25 to its normal position Since the variable Voltage impressed on galvanorneter 26 and potentiometer 21 from potentiometer iii] is proportional to speed, the position for balance of the arm of potentiometer 2'! is an indication of speed and is continuously traced through recording element 34 on a chart (not shown) carried by rotating recording drum Chart drive motor 32, which is mechanically connected to recording drum 33 for the rotation thereof, is controlled through a speed integrator 22 forming a part of speed-time recorder C. Speed integrator 22 is similar in construction and operation to acceleration integrator ill except that its output is adapted to control the operation of motor 32 by means of the mechanism shown in Fig. 6. In construction. and operation, integrator 22 may be of the type shown in U. S. Patent 2,309,790. Its operation is such as to integrate with respect to time the speed indications represented by successive positions of the movable arm of potentiometer It. The

result is therefore a value proportional to distance.

The operation of speed integrator 22 is used to control motor 32 through the mechanism shown Control device 4 in Fig. 6 in which the integrating shaft of speed integrator 22 is shown at 52. Mounted on shaft 10 acts to open switch 74.

62 are two notched cam elements 63 and 64 which are mounted so as to make circumferential contact, during a part of their rotation, with movable arms 65 and 66 forming parts of the switches 61 and 68. Through the action of rotating cams 63 and 64 the switches 61 and 58 are alternately opened and closed, the action being such that switch 61 is closed when switch 68 is open and vice versa. Attached to the drive shaft 69 of motor 32 are two additional cam members 10 and II which are mounted in such a way as to come in contact with the movable arms 12 and 13 of switches M and 15'. Switches 61, 68, 14 and 15 are interposed in one side of the line leading to motor 32 as shown in Fig. 6. The other side of the line is con nected directly to motor 32. With the cams E3, 64, it and H in the positions shown in Fig. 6 the motor 32 would be energized and would con-' tinue to run for so long as the relative posi-' tions of the various cams remained in correspondence. However, if shaft 62 ceases rotating with switch 6! closed, the continued operation of motor 32 will be interrupted as soon as cam Similarly, if shaft 62 stops in a position where switch 68 is closed, motor 32 will stop as soon as cam H opens switch 15. In either event motor 32 cannot be energized again until shaft 62 is caused to rotate. It will be noted that the switches and cams are so arranged that one switch of each pair is al ways open when the other isv closed. The effect of the arrangement shown in Fig. 6 is an intermittent operation of motor 32 in response to movements of the integrating shaft 62, since the integration at 22 is one of speed with respect to time the ultimate rotation of drum 33 is proportional to distance and the trace formed by indicating element 34 is one showing speed at any distance.

An additional trace is provided at recording drum 33 through indicating and recording element 43 which is mechanically actuated by time indicator 3! which has a mechanism adapted to move indicating and recording element 43 at a constant rate proportioned to time, automatically resetting at predetermined intervals. Details of time mechanism 3| are shown diagram+ matically in Fig. 5 in which synchronous motor 29 is shown connected to a shaft 15 through gears 11' and 18. Cam 1 is keyed to shaft 15 and engages cross-arm of movable bar at which carried indicating and recording element 43. Bar 8| is guided in slot 82 forming a part of guide member 83. Springs 84 are provided for holding cross-arm 8G in contact with cam 19 and are attached to fixed anchor elements 85. Since motor 29 operates continuously and at constant speed, the cam 79 rotates continuously in the direction indicated by the arrow. Starting from the position shown in Fig. 3 the eiTect of such rotationis to move bar 8| in the direction of guide member 83, thus moving indicating and recording element 43 outward. This motion will continue with the rotation of cam lSuntil threequarters of a revolution has been efi'iected from the position shown in Fig. 5. At this point crossarm 80 will be moved inwardly along the notched surface 86 through the action of springs 84. This cycle will then be repeated as cam 39 continues to rotate. The time required for a complete revolution of cam 19 is determined by the speed of motor 29 and the gear ratio between gears '11 and 78. At all events the speed. of rotation is constant and therefore the trace produced by indicating and recording element 43 as shown in Fig. 2 is one of time at any distance.

Potentiometer 37 with its external voltage source 38 is provided for making adjustments to the net tractive effort values derived from unit A at top speed. Such an adjustment is desirable in view of the fact that the net tractive effort of different locomotives varies as the speed approaches a maximum. Potentiometer 31 has a manually operable variable resistance which isset initially in the calibration of unit A.

Potentiometer 39, together with external voltage source 43 and automatic switch 41, is provided for automatically adjusting for the effect of the operation of air conditioning equipmenton net tractive effort values. It is desirable toprovide such a means in view of the fact that trains having air conditioning equipment normally have means for operating such equipmentabove a predetermined speed value. Power for the operation of the air conditioning equipment is derived from the operation of the train and. therefore reduces the net tractive eiTort available ior acceleration. Switch 4| is automatically operable to swing to the dotted position shown in. Fig. 3 when the speed value calculated and recorded by the device of the present invention reaches a predetermined figure which is normally about thirty miles per hour. Operation of switch 4! to the dotted position has the effect of removing potentiometer 39 and battery 40 from the net tractive eiiort circuit, and this has the effect of reducing the total net tractive effort available since it subtracts the voltage derived from. battery 43 from the total voltage being applied. to potentiometer l.

The operating details of switch 41 are shown diagrammatically in Fig. 4 in which the position of the various elements are shown at an indicated speed of about fifty miles per hour. The switch element itself is shown at 53 and comprises four contacts SI, 52, 53 and 54 and movable contact bar 55 which is adapted to connect contacts 5| and 52 in the up position and contacts 5S and 54 in the down position. Attached to contact bar 55 is the rod 56 which serves as the core for solenoid coil 51. One side of coil 5'! is connected directly to the external voltage supply. The other side of coil 51 is connected to the other side of the voltage supply through slide contact device 58 which consists of a metallic contact strip 59 extending around seven-tenths of a semicircle as shown. Device 58 also includes a sliding contact arm 60 which is moved by means of shaft 6! in response to movements at the main shaft 4 shown as a part of the speed-time recorder C in Fig. 3. It will be understood that shaft 6! is mechanically connected to shaft 44 at one end and to sliding contact arm 60 at the other. Coil 51 is energized when arm 50 is in contact with contact strip 59 and coil 51 is deenergized when such contact is broken, as will be the case when the position of arm 60 corresponds to a value of less than thirty miles per hour. When energized, solenoid coil 51 moves core 53 and contact bar 55 upward to the position shown in Fig. 4. At speeds less than thirty miles per hour core 56 and contact bar 55 move downward since coil 51 is then de-energized. This has the efiect of disconnecting points 5i and 52 and connecting points 53 and 54.

Potentiometer 35 and external voltage source 36 are provided for making available a voltage proportional to grade or braking. Such grade or braking adjustments are made by a manual ad- -justment of potentiometer by a setting of the .movable arm thereof to which may be attached a calibrated dial (not shown). With switch 5 in the braking position, manual adjustments of the movable arm of potentiometer 35 will result in the application of positive or negative voltages to acceleration-time unit B thus producing increased or decreased acceleration.

The operation of the device described above is as follows:

The primary circuit comprising unit A and potentiometers 'l, 35, 37 and 39 is first calibrated so that it operates to indicate on the recorder of unit B acceleration values as expressed on a curve of the type shown in Fig. 1. Operating speed restrictions, grades and braking lines are then plotted on a speed-distance chart as shown in Fig. 2. This plotted material includes all of the lines appearing on Fig. 2 except the time line and the acceleration curves marked E. This chart is then placed in position on recording drum 33. All measuring apparatus is placed in neutral or balanced position; movable arm 3 is moved to the zero miles per hour position on the tapped slide wire 2; switch 5 is moved to normal accelerating position as shown in Fig. 3; and the main power switch 42 is closed. Since the available acceleration will be at a maximum when movable arm 3 is at zero miles per hour position, the acceleration value at unit B will be at a maximum and therefore the speed determined by acceleration integrator l3 will begin to increase.

Y As such speed increases the movable arm 3 will be moved to successively higher speed indications by the action of shaft 44 as described above, and this will bring about a decrease in the available acceleration voltage and therefore a slowing down of the rate of increase of speed until such time as a balancing condition is reached or until the operator makes a change as indicated below. After setting the device in operation, the operator maintains control in such a way as to produce a curve on the speed-distance chart mounted on drum 33 which will include the heavy portions of the curves previously drawn on said chart and will record calculated performance throughout the desired range. To do this, the operator manipulates the variable adjustment on the calibrated dial of potentiometer 35 and at the same time moves the arm of switch 5 to the braking position when either grade or braking adjustments are indicated on the speed-distance chart. Thus with switch 5 in normal accelerating position the operator permits the speed to increase to follow the lines on the speed-distance chart. As soon as such acceleration has increased the speed to the value shown on the speed-distance chart, the operator moves switch 5 to the constant speed position until such time as it is necessary either to increase or decrease speed. An increase in speed is accomplished by returning switch 5 to the normal accelerating position. A decrease in speed is accomplished by moving switch 5 to the braking position and making the necessary braking adjustment at potentiometer 35. Continued speed at no increase is accomplished by moving switch 5 to the constant speed position. With these adjustments the operator is able to obtain a trace on the speed distance chart carried by recording drum 33 which will include the previously determined heavy portions of the curve and also the curves connecting said heavy portions. At the same time there will be obtained a curve on the chart carried by recording drum [4 indicating acceleration at any time, and a further curve on the chart carried by recording drum 23 indicating speed at any time. In this way the desired information is calculated over the entire range of operation and preserved on the recording charts.

Having thus described my invention, I claim:

In a device for calculating train performance data, means for producing a voltage proportional to tractive efiort, means for adjusting and calibrating said voltage to correspond with predetermined acceleration values for a plurality of train speeds, means including a self-balancing potentiometer and an acceleration integrator for producing a second voltage proportional to speed and means including a self-balancing potentiom- 10 eter and a speed integrator for producing an indication of distance.

SPENCER V. SMITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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