US3840096A - Electromagnetic rail brake - Google Patents

Electromagnetic rail brake Download PDF

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Publication number
US3840096A
US3840096A US00355218A US35521873A US3840096A US 3840096 A US3840096 A US 3840096A US 00355218 A US00355218 A US 00355218A US 35521873 A US35521873 A US 35521873A US 3840096 A US3840096 A US 3840096A
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United States
Prior art keywords
brake shoe
brake
rail
travel
elements
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00355218A
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English (en)
Inventor
G Tolksdorf
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Knorr Bremse AG
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Knorr Bremse GmbH
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Filing date
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Publication of US3840096A publication Critical patent/US3840096A/en
Assigned to KNORR-BREMSE AKTIENGESELLSCHAFT reassignment KNORR-BREMSE AKTIENGESELLSCHAFT CHANGE OF NAME (SEE DOCUMENT FOR DETAILS). EFFECTIVE ON 08/30/1985 Assignors: KNORR-BREMSE GESELLSCHAFT MIT BESCHRAENKTER HAFTUNG
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B61—RAILWAYS
    • B61H—BRAKES OR OTHER RETARDING DEVICES SPECIALLY ADAPTED FOR RAIL VEHICLES; ARRANGEMENT OR DISPOSITION THEREOF IN RAIL VEHICLES
    • B61H7/00—Brakes with braking members co-operating with the track
    • B61H7/02—Scotch-blocks, skids, or like track-engaging shoes
    • B61H7/04—Scotch-blocks, skids, or like track-engaging shoes attached to railway vehicles
    • B61H7/06—Skids
    • B61H7/08—Skids electromagnetically operated

Definitions

  • An electromagnetic rail brake for railroad vehicles has a plurality of yoke shaped brake shoe elements positioned successively in the direction of travel of the vehicle with the central portions of the elements extending through an excitation coil which has its axis transverse to the direction of travel.
  • Each brake shoe element comprises two halves which are bolted together and pole pieces are attached to the lowerends of each of the arms of the brake shoe elements so that a surface of the pole piece is engageable with the rail surface.
  • the brake shoe elements are madeof soft steel having high magnetic permeability and low magnetic coercive force and the pole pieces are of ferritic cast iron with globular graphite.
  • the pole pieces may be either triangular or quandrangular in shape when viewed vertically.
  • PATENTED BUY 8 4 SHEET 8 OF 6 ELECTROMAGNETIC RAIL BRAKE The present invention relates to an electromagnetic rail brake for railroad vehicles of the type comprising an excitation coil and a plurality of brake shoes positioned successively in the direction of travel and having pole pieces on the portions of the brake shoe elements facing the rail such that the pole pieces engage the rail during braking, more particularly, to the structure of the brake shoe element and pole piece and the materials from which they are made.
  • the brake shoe elements are generally yoke shaped so as to have a central portion extending through the excitation coil which is positioned with its axis transverse with respect to the direction of travel of the vehicle.
  • Each brake shoe element has a pair of vertical arms depending from its central portion with pole pieces attached to the lower ends of these arms.
  • the brake shoe should be constructed of a material which has maximum wear resistance in that it must be capable of resisting the wear produced by frequent sliding contact along a rail during braking.
  • the brake shoe must have maximum magnetic permeability in order to produce a maximum level of induction in the brake shoe and a resulting maximum force of attraction between the brake shoe and the rail in response to a given voltage which is passed through the excitation coil.
  • the brake shoe material must be characterized by a hysteresis loop that exhibits a low magnetic coercive force in order to obtain low hysteresis losses when the excitation coil is subjected to alternating current.
  • Electromagnetic rail brakes have been constructed wherein the brake shoes are subdivided into a plurality of movable segments in order to facilitate adaption of the brake shoe to the cross sectional shape of the head of the rail.
  • Brake shoes have also been mounted so as to be freely movable with respect to the arms of the electromagnet which arms are also movable with respect to the core of the coil of the electromagnet in order to obtain optimum contact between the brake shoe and the head of the rail.
  • the subdividing of the brake shoes into segments has the disadvantage that the segments may become welded together because of the friction heat generated during braking. Constructing the brake shoes so as to be freely movable has the disadvantage that considerable air gaps are formed and their high magnetic resistance makes it impossible to achieve the advantage of improved contact between the brake shoe and the rail.
  • an electromagnetic rail brake wherein the excitation coil is mounted within an elongated elliptical housing positioned parallel to the rail and carrying a brake shoe on its lower portion with the brake shoe comprising a plurality of yoke shaped members arranged side by side and capable of limited free movement in all directions.
  • the brake shoe comprising a plurality of yoke shaped members arranged side by side and capable of limited free movement in all directions.
  • An electromagneticrail brake has also been constructed so as to comprise an excitation coil having its axis positioned transverse of the direction of travel of the vehicle and a plurality of yoke shaped brake shoe elements extending through the coil and positioned side by side in the direction of travel and movable reciprocably between separation plates.
  • Such a construction has been found to be disadvantageous since during braking the brake shoe elements tilt slightly in the direction of travel of the vehicle so that the brake shoes do not contact uniformly the rail with the entire contact surface which is adjacent to the rail head. This has the effect of significantly lowering the efficiency of the brake. Also, the tilted pole pieces are worn so as to be rounded which shortens considerably the useful operating life of the brake shoe elements.
  • a pole piece can then be attached to each surface of the brake shoe element arm which is facing to ward the rail and it has even been proposed to construct the pole pieces so asto form the above men tioned projection on the one hand and to define the above mentioned recess on the other hand.
  • the pole pieces may be triangular or quadrangular in shape and a flat element of non-magnetic material can be positioned between adjacent pole pieces of different polarity with the flat non-magnetic element being attached on one of two adjacent pole pieces and in order to support such a pole piece extending the non-magnetic element beyond the end of the arm facing the pole piece of the actual brake shoe element.
  • the non-magnetic elements each have a surface which is flush with the surface of the pole piece contacting the rail but the non-magnetic member is made of a material which is softer and less wear resistant than the pole pieces. It is preferable to weld the pole pieces onto their corresponding brake shoe element arms and, similarly, the flat elements can be welded onto the corresponding pole pieces. Particularly in an electromagnetic rail brake constructed in this manner and utilizing the eddy-current effect, the brake shoe elements can comprise two halves bolted to each other.
  • every brake shoe must comply with a number of conditions and particularly the requirements relating to the characteristics of the material.
  • the material requirements are in mutual contradiction so that up to the present time, these requirements have not been met in present known rail brakes.
  • the components of the rail brake which conduct the magnetic flux during braking were made of a material having a good magnetic conductivity, such as soft steel.
  • the rate of wear greatly increases and this results in a rapid significant decrease in braking efficiency.
  • an electromagnetic rail brake for railroad vehicles may comprise an excitation coil having its axis transverse to the direction of travel of the vehicle and a plurality of brake shoe elements positioned side by side in the direction of travel.
  • the brake shoe elements are yoke shaped and each has a central portion extending through the coil.
  • a plurality of pole pieces are mounted on the surfaces of the arms of said brake shoe elements facing toward the rail surface.
  • the brake shoe elements are made of a soft steel having high magnetic permeability and low magnetic coercive force and the pole pieces are made of ferritic cast iron with globular graphite therein.
  • Each brake shoe element may consist of two halves that are bolted together and each brake shoe element has two pole pieces which are bolted to the ends of the element arms facing toward the rail.
  • the brake shoe elements are movably mounted between separation plates and two adjacent brake shoe elements partially overlap each other to prevent tilting in the direction of travel.
  • the pole pieces may be either triangular or quadrangular in shape.
  • a magnetic insulation element is preferably provided between adjacent pole pieces.
  • FIG. 1 is a top plan view of an electromagnetic rail brake incorporating the present invention
  • FIG. 2 is a side elevational view of the rail brake of FIG. 1;
  • FIG. 3 is a bottom plan view of the rail brake of FIG.
  • FIG. 4 is a front elevational view of a half of a brake shoe element incorporated in the rail brake of FIGS. 1-3;
  • FIG. 5 is a side elevational view as viewed from the right in FIG. 4;
  • FIG. 6 is a top plan view of the brake shoe element half of FIG. 4.
  • FIGS. 7-9 are views corresponding to those of FIGS. 4-6 of a modification of a brake shoe element half.
  • the electromagnetic rail brake comprises a frame 1 to which is attached a coil former 2 having mounted thereon an excitation coil 3 and separator plates 4.
  • the plates 4 are vertical and extend perpendicularly of the coil former 2 and are spaced in the direction of the longitudinal axis of the coil former.
  • the axis of excitation coil 3 extends perpendicularly to the longitudinal axis of the coil former 2.
  • the coil 3 is connected to a source of alternating voltage by means of cables 5 and 6.
  • the frame I is mounted on a railroad vehicle so as to be capable of being raised and lowered and is so positioncd that the coil former 2 is in parallel with one of the two rails on which the railroad vehicle is traveling.
  • the rail is in parallel with the longitudinal axis of the coil former 2 and is positioned just below this coil former.
  • Each brake shoe element 7 is positioned between two separator plates 4 and its central cross piece that connects its two downwardly depending arms passes through the central opening of the coil 3.
  • the brake shoe elements 7 taken as a whole form a brake shoe.
  • Each brake shoe element 7 consists of two identical halves, such as may be seen in FIGS. 4-6, with the halves being joined together by bolts 8. Each half has a triangular pole piece 10 mounted thereto by means of two bolts 9.
  • the pole piece 10 is substantially L- shaped and comprises a first horizontal arm which is attached by vertically positioned bolts 9 onto the lower surface 16 of brake shoe element 7.
  • the lower surface 16 is on the end of the lateral arm of the yoke shaped brake shoe element and this surface is facing toward the rail.
  • the other arm of pole piece 10 is connected or integral with the first arm on the end thereof which faces toward the vertical central longitudinal plane of the brake shoe element 9.
  • This second arm extends vertically downwardly and has a surface 17 which is engageable with the rail surface.
  • Each pole piece 10 consists of ferritic cast iron comprising spheroidal or nodular graphite therein according to German Industrial Standards (DIN 1693).
  • Each brake shoe element 7 or the halves of each element consists of a soft unalloyed steel of small carbon content having high magnetic permeability and low magnetic coercive force. Such a steel has a maximum carbon content of 0.25 percent and may be according to German Industrial Standards (DIN 17 100).
  • each half of each brake shoe element 7 is provided with a projection 11 extending in the direction of travel and each pole piece 10 of a half is mounted so as -to leave free a lower surface 12 on the projection 11 and to project on the opposite end of the half so as to define an upper surface 13 in the direction of travel.
  • each pole piece surface 13 engages surface 12 of projection 11 of the adjacent half of the next successive brake shoe element 7 upon which is mounted a pole piece 10 of like polarity.
  • each triangular pole piece 10 is positioned with its tip directed away from its bolts 9 and below the surface 12 of the opposite half of brake shoe element 7.
  • the tip of the pole piece is provided with a sloping surface 14 at its side which is adjacent to the surface 12 as can be seen in FIGS. 4-6.
  • Magnetically insulating flat elements 15 are positioned between adjacent pole pieces 10 of different polarity in order to avoid magnetic short circuits. These flat elements are attached to a pole piece 10 in each case and thus can be readily replaced together with the pole piece.
  • the insulation elements 15 are so mounted that their lower surfaces are in the same plane together with the triangular lower surfaces of all of the pole pieces 10 so that the insulating elements and pole pieces are in simultaneous contact with the rail surface during the braking operation. This structure provides for insulating magnetically the pole pieces from each other.
  • the pole pieces 10 consist of angular elements as can be clearly seen in FIG. 7.
  • the angular pole pieces 10 are provided with a substantially quadrangular surface which is in contact with the rail surface.
  • each quadrangular pole piece is attached to a brake shoe element half as also shown in FIGS. 7-9.
  • These pole pieces similarly are formed of ferritic cast iron having globular graphite therein and the brake shoe element 7 also consists. of soft steel having a high magnetic permeability and a low magnetic coercive force.
  • the brake shoe element 7 in FIGS. 7-9 are also provided with projections 11 each having a lower surface 12 as well as an upper surface 13 on pole piece 10 so that the elements can be arranged side by side partially overlapping each other in the same manner as described above.
  • the present invention is a highly effective yet simple embodiment of the concept that in order to obtain a high efficiency in an electromagnetic rail brake for railroad vehicles, the parts conducting the magnetic flux during braking should consist of a meterial having good magnetic conductivity and sections of these parts which increase as much as possible the resistance should be present in the magnetic circuit in order to obtain good braking efficiency over long periods of operation even in railroad vehicles that are operated at speeds exceeding miles per hour.
  • the pole pieces which are of lesser magnetic conductivity constitute only a small portion of the magnetic circuit and this portion is practically limited to the wearing surface with which the brake shoe contacts the rail surface.
  • the present invention can be incorporated in electromagnetic rail brakes utilizing lateral poles and also in connection with electromagnetic brakes comprising eddy-current poles.
  • An electromagnetic rail brake for railway vehicles comprising an excitation coil having its axis transverse to the direction of travel of the vehicle and parallel to the rail surface, a plurality of brake shoe elements of soft steel having high magnetic permeability and low magnetic coercive force positioned successively in the direction of travel, said brake shoe elements each being yoke shaped and each having a central portion and two vertical arms depending from the ends of said central portion, each brake shoe element having its central portion extending through said coil, the end surfaces of the arms of each of said brake shoe elements facing toward the rail surface, a pole piece on each of said arm end surfaces wherein each brake shoe element has two pole pieces bolted thereto, said pole pieces being of ferritic cast iron with nodule graphite.
  • each brake shoe element comprises two halves which are bolted together through the divided central portions.
  • An electromagnetic rail brake as claimed in claim 1 and comprising a coil former extending in the direction of travel of the vehicle, a plurality of separator plates spaced along said coil former, said brake shoe elements being moveably mounted between said separator plates, adjacent brake shoe elements partially overlapping each other to prevent tilting of the elements in the direction of travel of the vehicle.
  • each pole piece has an L-shape when viewed in the direction of travel and comprising a first arm fastened to the end surface of an arm on said brake shoe element and a second arm having a lower surface which is engageable with the surface of the rail.
  • each pole piece has a tip extending away from the arm end surface to which it is attached, the upper surface of said tip is sloping and extends below the downwardly directed horizontal surface of the other half of the brake shoe element.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Dynamo-Electric Clutches, Dynamo-Electric Brakes (AREA)
US00355218A 1972-04-28 1973-04-27 Electromagnetic rail brake Expired - Lifetime US3840096A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19722221051 DE2221051A1 (de) 1972-04-28 1972-04-28 Magnetschienenbremse

Publications (1)

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US3840096A true US3840096A (en) 1974-10-08

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US00355218A Expired - Lifetime US3840096A (en) 1972-04-28 1973-04-27 Electromagnetic rail brake

Country Status (6)

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US (1) US3840096A (de)
AT (1) AT334966B (de)
DE (1) DE2221051A1 (de)
FR (1) FR2182434A5 (de)
GB (1) GB1376101A (de)
IT (1) IT979856B (de)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3897117A (en) * 1973-07-20 1975-07-29 Knorr Bremse Gmbh Centering device for a rail brake magnet
US5862891A (en) * 1994-10-28 1999-01-26 Knorr-Bremse Systeme Fur Scheinenfahrzeuge Gmbh Electromagnetic or permanent-magnetic rail brake
US6041897A (en) * 1996-05-10 2000-03-28 Knorr-Bremse System Fur Schienenfahrzeuge Gmbh Magnetic brake linear eddy current brake
US6533083B1 (en) * 2000-02-15 2003-03-18 Magnetar Technologies, Inc Eddy current braking apparatus
US20040079597A1 (en) * 2000-02-28 2004-04-29 Lothar Schmied Suspension for a rail brake
US20070000741A1 (en) * 2005-06-30 2007-01-04 Pribonic Edward M Axial rotary eddy current brake with adjustable braking force
US20100011985A1 (en) * 2006-06-27 2010-01-21 Bombardier Transporatation Gmbh Chassis frame of a rail vehicle

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE8011873U1 (de) * 1980-04-30 1980-09-04 Knorr-Bremse Gmbh, 8000 Muenchen Schienenbremsmagnet fuer magnetschienenbremsen von schienenfahrzeugen
DE3108184A1 (de) * 1981-03-04 1982-09-16 Knorr-Bremse GmbH, 8000 München "schienenbremsmagnet"
NL9402145A (nl) * 1994-12-16 1996-08-01 Transferia Systems Bv Magnetische railreminrichting.

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1793757A (en) * 1927-02-05 1931-02-24 William H Smith Process of uniting iron with other metals and elements
GB438997A (en) * 1934-11-12 1935-11-27 Knorr Bremse Ag Improvements in or relating to electromagnetic track brakes
US2054716A (en) * 1931-11-16 1936-09-15 Stedefeld Electromagnetic rail brake
US2207151A (en) * 1937-08-11 1940-07-09 Transit Res Corp Brake shoe
US2542788A (en) * 1946-12-12 1951-02-20 Freins Jourdain Monneret Sa Electromagnetic brake for rail vehicles
FR1084784A (fr) * 1952-10-28 1955-01-24 Knorr Bremse Gmbh Frein magnétique sur rail

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1793757A (en) * 1927-02-05 1931-02-24 William H Smith Process of uniting iron with other metals and elements
US2054716A (en) * 1931-11-16 1936-09-15 Stedefeld Electromagnetic rail brake
GB438997A (en) * 1934-11-12 1935-11-27 Knorr Bremse Ag Improvements in or relating to electromagnetic track brakes
US2207151A (en) * 1937-08-11 1940-07-09 Transit Res Corp Brake shoe
US2542788A (en) * 1946-12-12 1951-02-20 Freins Jourdain Monneret Sa Electromagnetic brake for rail vehicles
FR1084784A (fr) * 1952-10-28 1955-01-24 Knorr Bremse Gmbh Frein magnétique sur rail

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3897117A (en) * 1973-07-20 1975-07-29 Knorr Bremse Gmbh Centering device for a rail brake magnet
US5862891A (en) * 1994-10-28 1999-01-26 Knorr-Bremse Systeme Fur Scheinenfahrzeuge Gmbh Electromagnetic or permanent-magnetic rail brake
US6041897A (en) * 1996-05-10 2000-03-28 Knorr-Bremse System Fur Schienenfahrzeuge Gmbh Magnetic brake linear eddy current brake
US6533083B1 (en) * 2000-02-15 2003-03-18 Magnetar Technologies, Inc Eddy current braking apparatus
US20040079597A1 (en) * 2000-02-28 2004-04-29 Lothar Schmied Suspension for a rail brake
US6769517B2 (en) 2000-02-28 2004-08-03 Knorr-Bremse Systeme Fur Schienenfahrzeuge Gmbh Suspension for a rail brake
US20070000741A1 (en) * 2005-06-30 2007-01-04 Pribonic Edward M Axial rotary eddy current brake with adjustable braking force
US20100011985A1 (en) * 2006-06-27 2010-01-21 Bombardier Transporatation Gmbh Chassis frame of a rail vehicle
US8196522B2 (en) * 2006-06-27 2012-06-12 Bombardier Transportation Gmbh Chassis frame of a rail vehicle

Also Published As

Publication number Publication date
FR2182434A5 (de) 1973-12-07
DE2221051A1 (de) 1973-11-08
ATA364773A (de) 1976-06-15
GB1376101A (en) 1974-12-04
AT334966B (de) 1977-02-10
IT979856B (it) 1974-09-30

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Owner name: KNORR-BREMSE AKTIENGESELLSCHAFT

Free format text: CHANGE OF NAME;ASSIGNOR:KNORR-BREMSE GESELLSCHAFT MIT BESCHRAENKTER HAFTUNG;REEL/FRAME:004495/0631

Effective date: 19851018