US3333417A - Hydraulic testing means - Google Patents

Hydraulic testing means Download PDF

Info

Publication number
US3333417A
US3333417A US400724A US40072464A US3333417A US 3333417 A US3333417 A US 3333417A US 400724 A US400724 A US 400724A US 40072464 A US40072464 A US 40072464A US 3333417 A US3333417 A US 3333417A
Authority
US
United States
Prior art keywords
liquid
hydraulic
chamber
ram
pressure
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
Application number
US400724A
Inventor
Hinde Philip Benjamin
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.)
Individual
Original Assignee
Individual
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Application granted granted Critical
Publication of US3333417A publication Critical patent/US3333417A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
    • F15B2211/205—Systems with pumps
    • F15B2211/2053—Type of pump
    • F15B2211/20538—Type of pump constant capacity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/405—Flow control characterised by the type of flow control means or valve
    • F15B2211/40515—Flow control characterised by the type of flow control means or valve with variable throttles or orifices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/41—Flow control characterised by the positions of the valve element
    • F15B2211/413—Flow control characterised by the positions of the valve element the positions being continuously variable, e.g. as realised by proportional valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/415—Flow control characterised by the connections of the flow control means in the circuit
    • F15B2211/41509—Flow control characterised by the connections of the flow control means in the circuit being connected to a pressure source and a directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/40—Flow control
    • F15B2211/42—Flow control characterised by the type of actuation
    • F15B2211/421—Flow control characterised by the type of actuation mechanically
    • F15B2211/423—Flow control characterised by the type of actuation mechanically manually, e.g. by using a lever or pedal
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/505—Pressure control characterised by the type of pressure control means
    • F15B2211/50563—Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure
    • F15B2211/50572—Pressure control characterised by the type of pressure control means the pressure control means controlling a differential pressure using a pressure compensating valve for controlling the pressure difference across a flow control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • F15B2211/515—Pressure control characterised by the connections of the pressure control means in the circuit
    • F15B2211/5151—Pressure control characterised by the connections of the pressure control means in the circuit being connected to a pressure source and a directional control valve
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7052—Single-acting output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
    • F15B2211/7051—Linear output members
    • F15B2211/7053—Double-acting output members
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
    • F15B2211/76—Control of force or torque of the output member
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S60/00—Power plants
    • Y10S60/907—Working member positioned against counterforce by constantly applied motive fluid

Definitions

  • Certain hydraulic testing machines have been proposed which operate by delivering hydraulic liquid to a ram at a constant volumetric rate independent of the pressure produced in said liquid.
  • a specimen being acted upon by the ram is continually and increasingly strained and measurements can be intermittently or continually taken of the load produced on the specimen and of the resulting deflection for determination of the characteristics of the specimen and its material.
  • the hydraulic liquid may be delivered to the ram at a constant volumetric rate
  • the specimen is not strained at a corresponding rate because the elasticity in the ram and also in the liquid supply system to the ram comprising for example delivery pipes, and devices for controlling and measuring the pressure in the liquid, provides a varying capacity for the liquid.
  • the elasticity of the liquid itself also results in a varying liquid volumes. For this reason, the testing machine has in practice a finite stiffness.
  • the deformed elastic parts and the liquid store potential energy which is released when the pressure of the liquid falls and thus maintains said pressure at a higher value than would exist if the supply system and liquid were completely non-elastic, i.e., if the testing machine were rigid or infinitely stiff.
  • the maintenance of pressure by the released potential energy undesirably continues the increas ing deflection without control, and a constant deflection rate is lost.
  • the invention consists in a stiffness adjuster for use in hydraulically powered testing apparatus comprising a ram and a supply system to supply hydraulic liquid to said ram, said stiffness adjuster comprising means responsive to increasing liquid pressure in said system and ram for decreasing the hydraulic liquid capacity of the supply system and ram.
  • FIGURE 1 is a diagrammatic sectional view of a stiffness adjuster in accordance with the invention.
  • FIGURE 2 is a diagrammatic sectional view of a conventional hydraulic testing machine.
  • FIGURE 1 shows a stiffness adjuster 5 which comprises two cylinders 6, 7 secured together in co-axial alignment by tie rods 8 extending between flanges 9 and 10 one on each of the cylinders 6, 7.
  • the cylinders 6, 7 contain co-axial pistons 11 and 12 respectively of different crosssectional areas joined together so that as one piston 11 or 12 sinks more deeply into its cylinder so the other piston 12 or 11 partially emerges from its 3,333,417 Patented Aug. 1, 1967 cylinder.
  • a compressed helical spring 13 bears against the end 14 of the larger piston 11 between the cylinders 6, 7, encircles the smaller piston 12, and at its other end abuts the inner end of cylinder 7.
  • Each cylinder 6 or 7 is provided with an inlet/outlet passage 15, 16 respectively for connection into the hydraulic circuit of a testing machine.
  • the inlet/ outlet passage 15 leading from the cylinder 6 includes a stop valve 17.
  • the stiffness adjuster 5 is connected into the hydraulic testing machine as shown in FIGURE 2.
  • the testing machine comprises a pump 18 for supplying hy draulic liquid from a reservoir 20 to the main chamber 19 of a control device.
  • an adjustable needle valve 21 controls communication between chamber 19 and the supply system 22.
  • the supply system 22 includes a delivery pipe 23 leading to a hydraulic ram 24 for straining a specimen (not shown), and a branch pipe 25 leading from the delivery pipe 23 to a secondary chamber 26 housing a compression spring 27 bearing against one end 28 of a control piston 29.
  • the other end 30 of the piston 29 is for closing a leak passage 31 between the main chamber 19 and the reservoir 20.
  • the inlet/outlet passage 15 of the cylinder 6 is connected to the main chamber 19, and the inlet/outlet passage 16 is connected to the delivery pipe 23 so that the constant pressure difference also exists between the liquid parts within the cylinders 6, 7.
  • said liquid parts are acting on pistons 11, 12 of different crosssectional areas so that, as the pressures increase, the larger piston 11 will progressively move out of its cylinder 6 against the action of the spring 13, and the smaller piston 12 will move into its cylinder 7 and thus displace some of the liquid from the latter into the supply system 22, thereby effectively decreasing the capacity of said system.
  • the reverse changes take place and the capacity of the supply system 22 is increased.
  • the amount of adjustment required of the stiffness adjuster 5 can be provided by calculating the change of capacity needed to be produced by the adjuster from zero to maximum pressure in the supply system 22, arranging for the smaller piston 12 to effect this change over its total travel, and choosing a spring 13 and diameter of the larger piston 11 to produce this travel over this total pressure range. Thereafter adaptation of the adjuster can be made by substitution of a different spring 13 to alter the amount of adjustment produced by the adjuster 5 and hence produce a different stiffness.
  • the adjuster 5 may include means for promoting angular oscillation of or rotation of its pistons 11, 12 to minimise frictional effects.
  • stiffness adjuster 5 has been described as applied to a hydraulic testing machine, said adjuster is also applicable to other hydraulic testing apparatus such as hydraulic testing rigs or frames in which the testing means are not self-contained but depend structurally upon a part or parts of buildings or the specimens themselves.
  • a hydraulic testing machine of the type comprising a hydraulic ram, a hydraulic system having a chamber receiving said ram and connected to receive hydraulic liquid from a source for displacing said ram against a load applied thereto, and means for maintaining a substantially constant pressure differential between said source and said chamber for delivering said liquid to said chamber at a constant volumetric rate independent of variations of liquid in said chamber resulting from the magnitude of the load applied to said ram, means responsive to the liquid pressures at said cource and said chamber for compensating for the elasticity of the liquid in said system and for the elasticity of ram and the component parts defining said system by inversely varying the volumetric capacity in said system with respect to the liquid pressure in said chamber.
  • said compensating means comprises a compound piston having (a) a large diametered section received in a first cylinder section and connected by first passage means directly to said source and (b) a smaller diametered section received in a second cylinder section and connected by second passage means directly to said chamber, said compound piston being (a) displaceable by increase of liquid pressures in said chamber and at said source to displace liquid from said second cylinder section into said system and (b) displaceable by decrease of liquid pressures in said chamber and at said source to enable liquid in said system to flow into said second cylinder section.

Landscapes

  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Health & Medical Sciences (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)

Description

1967 P. B. HINDE 3,333,417
HYDRAULI C TEST ING MEANS Filed Oct. 1, 1964 PHIL) P BENJA HN HINDE United States Patent 39,518/ 63 4 Claims. (Cl. 60-545) This invention relates to hydraulically powered physical testing apparatus and more especially, but not exclusively, to machines for use in the determination of load/deflection or stress/strain characteristics of materials.
Certain hydraulic testing machines have been proposed which operate by delivering hydraulic liquid to a ram at a constant volumetric rate independent of the pressure produced in said liquid. In consequence a specimen being acted upon by the ram is continually and increasingly strained and measurements can be intermittently or continually taken of the load produced on the specimen and of the resulting deflection for determination of the characteristics of the specimen and its material.
It has been found that in general, although the hydraulic liquid may be delivered to the ram at a constant volumetric rate, the specimen is not strained at a corresponding rate because the elasticity in the ram and also in the liquid supply system to the ram comprising for example delivery pipes, and devices for controlling and measuring the pressure in the liquid, provides a varying capacity for the liquid. In addition the elasticity of the liquid itself also results in a varying liquid volumes. For this reason, the testing machine has in practice a finite stiffness.
Further, the deformed elastic parts and the liquid store potential energy which is released when the pressure of the liquid falls and thus maintains said pressure at a higher value than would exist if the supply system and liquid were completely non-elastic, i.e., if the testing machine were rigid or infinitely stiff. Thus, if during a test a specimen reaches its yield point and commences to deflect at an increasing rate so that the pressure in the liquid falls, the maintenance of pressure by the released potential energy undesirably continues the increas ing deflection without control, and a constant deflection rate is lost.
It is an object of the invention to provide a stiffness adjuster for use in a testing machine whereby the natural stiifnas of the machine determined by its construction and the hydraulic liquid used can be adjusted to a higher value.
The invention consists in a stiffness adjuster for use in hydraulically powered testing apparatus comprising a ram and a supply system to supply hydraulic liquid to said ram, said stiffness adjuster comprising means responsive to increasing liquid pressure in said system and ram for decreasing the hydraulic liquid capacity of the supply system and ram.
A typical example of the practical relationship of the invention will now be described with reference to the accompanying drawings in which:
FIGURE 1 is a diagrammatic sectional view of a stiffness adjuster in accordance with the invention; and
FIGURE 2 is a diagrammatic sectional view of a conventional hydraulic testing machine.
FIGURE 1 shows a stiffness adjuster 5 which comprises two cylinders 6, 7 secured together in co-axial alignment by tie rods 8 extending between flanges 9 and 10 one on each of the cylinders 6, 7. The cylinders 6, 7 contain co-axial pistons 11 and 12 respectively of different crosssectional areas joined together so that as one piston 11 or 12 sinks more deeply into its cylinder so the other piston 12 or 11 partially emerges from its 3,333,417 Patented Aug. 1, 1967 cylinder. A compressed helical spring 13 bears against the end 14 of the larger piston 11 between the cylinders 6, 7, encircles the smaller piston 12, and at its other end abuts the inner end of cylinder 7. Each cylinder 6 or 7 is provided with an inlet/ outlet passage 15, 16 respectively for connection into the hydraulic circuit of a testing machine. The inlet/ outlet passage 15 leading from the cylinder 6 includes a stop valve 17.
In use the stiffness adjuster 5 is connected into the hydraulic testing machine as shown in FIGURE 2. The testing machine comprises a pump 18 for supplying hy draulic liquid from a reservoir 20 to the main chamber 19 of a control device. In said device an adjustable needle valve 21 controls communication between chamber 19 and the supply system 22. The supply system 22 includes a delivery pipe 23 leading to a hydraulic ram 24 for straining a specimen (not shown), and a branch pipe 25 leading from the delivery pipe 23 to a secondary chamber 26 housing a compression spring 27 bearing against one end 28 of a control piston 29. The other end 30 of the piston 29 is for closing a leak passage 31 between the main chamber 19 and the reservoir 20.
When the testing machine is straining the specimen in a test, the pressure of the liquid in the secondary chamber 26, which is equal to the pressure in the delivery pipe 23, plus the pressure of the spring 27, acts on the end 28 of the control piston 29, whereas the pressure of the liquid in the main chamber 19 acts upon the end 30 of the control piston 29. Consequently when the forces on the .two ends of the control piston 29 equalise the control piston 29 allows surplus liquid output for the pump to leak back to the reservoir 20 through the passage 31, and a constant pressure difference corresponding to the forces of the compression spring 27 exists between the liquid parts acting on the control piston 29, and so will also exist across the needle valve 21 so that liquid is delivered to the supply system 22 through the valve 21 at a constant, rate for any given setting of the needle valve 21. If the pressure in the supply system 22 should suddenly drop (more especially due to a sudden yielding in the specimen), the leak passage 31 will be further opened until the original pressure difference is restored.
The inlet/outlet passage 15 of the cylinder 6 is connected to the main chamber 19, and the inlet/outlet passage 16 is connected to the delivery pipe 23 so that the constant pressure difference also exists between the liquid parts within the cylinders 6, 7. However, said liquid parts are acting on pistons 11, 12 of different crosssectional areas so that, as the pressures increase, the larger piston 11 will progressively move out of its cylinder 6 against the action of the spring 13, and the smaller piston 12 will move into its cylinder 7 and thus displace some of the liquid from the latter into the supply system 22, thereby effectively decreasing the capacity of said system. As the pressures fall, the reverse changes take place and the capacity of the supply system 22 is increased. Thus these changes in capacity of the supply system 22 are the reverse of the capacity changes taking place through the deformation of elastic parts in the supply system 22 and the liquid under changing pressure. Consequently the stiffness of the machine is increased, and may be increased to infinity if exact adjustment is arranged.
The amount of adjustment required of the stiffness adjuster 5 can be provided by calculating the change of capacity needed to be produced by the adjuster from zero to maximum pressure in the supply system 22, arranging for the smaller piston 12 to effect this change over its total travel, and choosing a spring 13 and diameter of the larger piston 11 to produce this travel over this total pressure range. Thereafter adaptation of the adjuster can be made by substitution of a different spring 13 to alter the amount of adjustment produced by the adjuster 5 and hence produce a different stiffness.
It is found that, when the testing machine described is used complete with the stiffness adjuster, a specimen being tested is strained at a rate corresponding to the rate of liquid delivered to the supply system 22 to a greater extent than Without the adjuster 5, and the release of potential energy occurring during decreasing pressure tends to maintain the pressure in the liquid to a lower extent than without the adjuster 5.
To improve the response to the adjuster 5 it may include means for promoting angular oscillation of or rotation of its pistons 11, 12 to minimise frictional effects.
Whereas the stiffness adjuster 5 has been described as applied to a hydraulic testing machine, said adjuster is also applicable to other hydraulic testing apparatus such as hydraulic testing rigs or frames in which the testing means are not self-contained but depend structurally upon a part or parts of buildings or the specimens themselves.
I claim:
1. In a hydraulic testing machine of the type comprising a hydraulic ram, a hydraulic system having a chamber receiving said ram and connected to receive hydraulic liquid from a source for displacing said ram against a load applied thereto, and means for maintaining a substantially constant pressure differential between said source and said chamber for delivering said liquid to said chamber at a constant volumetric rate independent of variations of liquid in said chamber resulting from the magnitude of the load applied to said ram, means responsive to the liquid pressures at said cource and said chamber for compensating for the elasticity of the liquid in said system and for the elasticity of ram and the component parts defining said system by inversely varying the volumetric capacity in said system with respect to the liquid pressure in said chamber.
2. The hydraulic testing machine defined in claim 1 wherein said compensating means comprises a compound piston having (a) a large diametered section received in a first cylinder section and connected by first passage means directly to said source and (b) a smaller diametered section received in a second cylinder section and connected by second passage means directly to said chamber, said compound piston being (a) displaceable by increase of liquid pressures in said chamber and at said source to displace liquid from said second cylinder section into said system and (b) displaceable by decrease of liquid pressures in said chamber and at said source to enable liquid in said system to flow into said second cylinder section.
3. The hydraulic testing machine defined in claim 2 1,467,522 9/1923 Amsler -52 2,102,865 12/1937 Vickers 6052 MARTIN P. SCHWADRON, Primary Examiner.
ROBERT R. BUNEVICH, Assistant Examiner.

Claims (1)

1. IN A HYDRAULIC TESTING MACHINE OF THE TYPE COMPRISING A HYDRAULIC RAM, A HYDRAULIC SYSTEM HAVING A CHAMBER RECEIVING SAID RAM AND CONNECTED TO RECEIVE HYDRAULIC LIQUID FROM A SOURCE FOR DISPLACING SAID RAM AGAINST A LOAD APPLIED THERETO, AND MEANS FOR MAINTAINING A SUBSTANTIALLY CONSTANT PRESSURE DIFFERENTIAL BETWEEN SAID SOURCE AND SAID CHAMBER FOR DELIVERING SAID LIQUID TO SAID CHAMBER AT A CONSTANT VOLUMETRIC RATE INDEPENDENT OF VARIATIONS OF LIQUID IN SAID CHAMBER RESULTING FROM
US400724A 1963-10-08 1964-10-01 Hydraulic testing means Expired - Lifetime US3333417A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB39518/63A GB1059113A (en) 1963-10-08 1963-10-08 Improvements relating to hydraulic testing means

Publications (1)

Publication Number Publication Date
US3333417A true US3333417A (en) 1967-08-01

Family

ID=10409994

Family Applications (1)

Application Number Title Priority Date Filing Date
US400724A Expired - Lifetime US3333417A (en) 1963-10-08 1964-10-01 Hydraulic testing means

Country Status (3)

Country Link
US (1) US3333417A (en)
DE (1) DE1258145B (en)
GB (1) GB1059113A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3688500A (en) * 1969-09-17 1972-09-05 Marcel Georges Chancel Fluid pressure system for obtaining, controlling or correcting micrometric displacements in machine-tools and other apparatus

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4572001A (en) * 1984-01-30 1986-02-25 Queen's University At Kingston Method and apparatus for measuring thermodynamic response

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1467522A (en) * 1921-03-31 1923-09-11 Amsler Alfred Pressure-control valve
US2102865A (en) * 1934-06-20 1937-12-21 Vickers Inc Combined flow control and relief valve

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1467522A (en) * 1921-03-31 1923-09-11 Amsler Alfred Pressure-control valve
US2102865A (en) * 1934-06-20 1937-12-21 Vickers Inc Combined flow control and relief valve

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3688500A (en) * 1969-09-17 1972-09-05 Marcel Georges Chancel Fluid pressure system for obtaining, controlling or correcting micrometric displacements in machine-tools and other apparatus

Also Published As

Publication number Publication date
DE1258145B (en) 1968-01-04
GB1059113A (en) 1967-02-15

Similar Documents

Publication Publication Date Title
US2592613A (en) Self-compensating accumulator
US1467522A (en) Pressure-control valve
GB1112494A (en) Improvements in and relating to training apparatus
CA1058058A (en) Power piston apparatus
GB1164003A (en) Apparatus for providing High-Pressure Liquid
US2479759A (en) Apparatus for the treatment of webs or fleeces
US3564883A (en) Hydraulic press control
US2167328A (en) Load maintainer for materials testing apparatus
US3333417A (en) Hydraulic testing means
US2344133A (en) Fluid system control
US5158676A (en) Chromatography apparatus
US3100986A (en) Leakage indicator
CN109883848A (en) The all-hydraulic non-servo creep of rock experimental rig of one kind and method
US4770094A (en) Control valve for regulating a pressure ratio between two pressure systems
US4328778A (en) Device for controlling a diesel motor driven pump drive
US3289406A (en) Hydraulic transmission devices
US2204434A (en) Rolling mill
GB1106448A (en) Improvements in dynamometers for well pumps
US2913985A (en) Hydraulic pumps
US3511050A (en) Transducer for converting fluid pressure oscillations into mechanical oscillations
US2038272A (en) Servomotor control
US3070146A (en) System and related device for balancing hydraulic presses in general
ES414434A1 (en) Device for maintaining a working fluid under a predetermined pressure
US2081404A (en) Process and apparatus for applying alternating positive and negative loads
US2348695A (en) Tension indicator and control