Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02F—DREDGING; SOIL-SHIFTING
  • E02F3/00—Dredgers; Soil-shifting machines
  • E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
  • E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
  • E02F3/36—Component parts
  • E02F3/38—Cantilever beams, i.e. booms;, e.g. manufacturing processes, forms, geometry or materials used for booms; Dipper-arms, e.g. manufacturing processes, forms, geometry or materials used for dipper-arms; Bucket-arms
  • E02F3/382—Connections to the frame; Supports for booms or arms
  • E02F3/386—Connections to the frame; Supports for booms or arms the boom being laterally shiftable relative to the frame

Definitions

• the present invention relates to hydraulic actuation of a sliding carriage guided for movement along a linear path.
• a backhoe is an item of excavating equipment comprising a digging bucket on the end of a two-part articulated arm, the two parts being termed a main boom and a dipper.
• Backhoes are typically mounted on the back of a vehicle, such as a tractor or front loader, and can be used for example to dig trenches.
• the present invention is concerned with a hydraulic system which may serve the purpose of the fluid operated ram in EP 0 692 579 but may alternatively be used to move any carriage that is guided for movement along a linear path.
• FIGS 1 and 2 of the accompanying drawings show different positions of a hydraulic system described in EP 1 264 938 which is believed to represent the closest prior art to the present invention and is incorporated herein by reference.
• This system uses only rams to move the king post assembly of a backhoe from one end position to the other.
• the system uses two hydraulic cylinders arranged "in series". By this, it is meant that the total possible displacement of the carriage is equal to the sum of the strokes of the individual cylinders.
• the illustrated arrangement is preferred to the other embodiment described in EP 1 264 938 which uses a cylinder with telescopically collapsible piston rods because it allows the cylinder body to be guided so as to maintain the pistons rods and cylinders in axial alignment when under load.
• the sliding carriage is designated 10 and it is constituted by a king post assembly on which the boom arm of a backhoe is pivoted.
• the carriage 10 is guided to slide along a stationary support frame 12 mounted transversely on the vehicle body, so that the carriage can move from an extreme left position, shown in Figure 1 , to an extreme right position, shown in Figure 2.
• the carriage 10 is moved by a two hydraulic jacks or rams 14 and 16 arranged in series with one another.
• the cylinders 14a and 16a of the two jacks are secured to one another and to a slotted guide plate 18 that receives a pin 20 secured to the carriage 10 by a fixed bracket (not shown).
• the end of the piston rod 14b of the upper jack 14 is connected by a pivot 22 to the support frame 22 while the free end of the rod 16b of the jack 16 is connected by a pin pivot 24 to a bracket 26 projecting from the right hand side of the carriage 10.
• the present invention provides an improved hydraulic system that avoids several shortcomings of the system illustrated in Figures 1 and 2, which will now be explained.
• the separation between the pivot pins 22 and 24 in the position of Figure 2 is equal to the full width of the guide frame 12. Consequently, when pressure is applied to move the carriage to this position, the force tending to bend the piston rods out of augment with the cylinders is a maximum. Furthermore, the pin 20 in this right hand position of the carriage 10 is at the very end of the cylinder of the upper jack 14 so that the pin 20 has little effect to prevent the piston rod 14b from being bent out of alignment with its cylinder 14a.
• the jacks 14 and 16 are not equally effective in both directions because each of their pistons has a large surface area on one side and a smaller surface area on the side connected to the piston rod.
• the piston surfaces used to return the carriage to the position shown in Figure 1 are the smaller annular surfaces.
• the present invention provides a hydraulic system for moving a carriage guided for movement along a linear path by a support frame, the system comprising two hydraulic jacks, each having a cylinder body and a piston rod, wherein the cylinder bodies of the two jacks are joined to one another, the end of the piston rod of one jack is connected to the support frame and the end of the piston rod of the other jack is connected to the carriage, characterised in that the two piston rods project from the same side of the joined cylinder bodies and in each end position of the carriage, the piston rod of a respective one of the jacks is fully extended while that of the other jack is fully retracted.
• the two jacks have strokes of unequal length and the second piston rod is connected to the side of the carriage that is nearer to the side of the frame connected to the first piston rod.
• the joined cylinders are formed with a projecting pin engaged in a slot in a guide movable with the carriage in order to prevent misalignment between the axes of the piston rods and the cylinders when under load.
• Figures 1 and 2 show a hydraulic system as taught by EP 0 692 579, and
• Figures 3, 4 and 5 show a hydraulic system of the present invention in different positions of the carriage.
• the hydraulic circuit of Figures 3 to 5 used two jacks 1 14, 116 of unequal stroke length and with their respective piston rods 114b and 116b projecting in the same direction from the cylinders 1 14a and 1 16a.
• the end of the piston rod 114b of the longer jack 116 is connected to the frame 1 12 by a pivot pin 122 while the end of the piston rod 116b of the shorter jack 116 is connected by a pivot pin 124 to a bracket 126 secured to the carriage 110.
• the pin 124 is located on the left side of the carriage 110, that is to say the side nearer the side of the frame 112 connected to the piston rod 114b.
• a guide plate 118 secured to the carriage 1 10 has a slot which receives a pin 120 fixed to joined cylinders 114a and 116a near to the end of the cylinder 1 16a from which the piston rod 1 16b projects. It would be possible to secure the slotted guide plate 1 18 to the cylinders 1 14a, 116a and the pin to the carriage 110 as was the case in the hydraulic circuit of Figures 1 and 2.
• bracket 126 does not project beyond the side of the frame, it does not interfere with the carriage reaching either of its end position.
• the hydraulic system can be mounted above the carriage where it is less exposed to dirt. Furthermore, it is readily possible to mount a fixed shield on the frame 22 to protect the piston rod 1 14b when it is extended. Another shield may be fixed to the underside of the part of the hydraulic cylinder 114a that projects beyond the cylinder 1 16a to protect the piston rod 116b when it is extended.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Mining & Mineral Resources (AREA)
• Civil Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structural Engineering (AREA)
• Actuator (AREA)
• Forklifts And Lifting Vehicles (AREA)

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Publications (1)

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Citations (6)

Family Cites Families (7)

• 2009
  • 2009-06-03 IT IT000421A patent/ITTO20090421A1/it unknown
• 2010
  • 2010-06-02 WO PCT/EP2010/057748 patent/WO2010139748A1/en active Application Filing
  • 2010-06-02 RU RU2011153695/03A patent/RU2559242C2/ru active
  • 2010-06-02 US US13/375,761 patent/US20120144998A1/en not_active Abandoned
  • 2010-06-02 EP EP10723105A patent/EP2438241B1/en active Active

Patent Citations (6)

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