Details of Hydraulic Cylinders and it’s usability in Industrial and Mechanical field

Hydraulic cylinders

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Hydraulic cylinders transform hydrostatic power into mechanical power. They’re considered as actuators or motors able to produce work. However, hydraulic cylinders vary from hydraulic motors since they carry out a linear (translatory) movement rather than a rotary movement. Thus, the cylinders are also known as linear motors.

Exactly How Much Force Can You Get? Understand the Mathematics behind Hydraulic Cylinders that given below:

The utmost cylinder force F relies upon the maximum operating pressure p and the section of the piston (effective area A). At constant pressure, a cylinder having a larger effective area A will generate a larger force F. At higher pressures, the force F will be larger:

F = p • A [in kN]

You need hydraulic cylinders to complete particular sorts of work: as an example, in applications such as those where loads must be lowered, lifted, locked or moved.

Types of Hydraulic Cylinders

In hydraulic cylinders, two functional types are generally known: “double acting and “single acting” cylinders. Only rapid traverse cylinders and telescopic cylinders can be found as either “double acting or “single acting” cylinders. Regarding function, it’s possible to sort out hydraulic cylinders as below:

Single-Acting Cylinders

  • Push-action cylinders
  • Pull-action cylinders
  • Telescopic cylinders
  • Rapid traverse cylinders

Double-Acting Cylinders

  • Differential cylinders
  • Double rod cylinders
  • Tandem cylinders
  • Telescopic cylinders
  • Rapid traverse cylinders

Single acting cylinders have one effective area, found on the bottom side, which can exert force in single direction only. For most hydraulic systems, these are typically designed as plunger cylinders and an alternative force is needed to send back the piston to the starting position: e.g. upstroke presses, lifting devices etc.

If there’s no force to send back the piston to the starting position, springs must be placed. This is often possible with small cylinders simply because of the limited force and stroke length of the return springs.

Telescopic cylinders are widely-used in hydraulic lifting purposes, or where large amplitudes are essential but only a little space is available, e.g. tipper trucks. The single acting or double acting differential cylinder is usually used in industrial and mobile hydraulic systems. The most common design concepts of the hydraulic differential cylinder in mill type and tie rod design is discussed below.

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Tie Rod Cylinder

Tie rod cylinders are widely-used in machine tools, the transfer lines, automotive industry and plastics machinery along with other manufacturing devices. The key feature of the tie-rod cylinder is its space saving compact design that makes it particularly ideal in manufacturing devices.

Key features of the tie-rod hydraulic cylinders:

  • Compact design
  • Limited piston diameter
  • Wide mounting range
  • Limited stroke length

The top and bottom of the tie-rod cylinder, together with the cylinder barrel, are connected together via four tie-rods. Extended tie-rods at the head or base of the cylinder is often used to mount the tie-rod cylinder. Threaded holes and sub-plate mounting alternatives are included as well in the wide mounting range of the tie-rod cylinder.

Typical parameters are:

  • Nominal pressure: up to 200 bar
  • Maximum stroke length: 2,000+ mm
  • Maximum stroke speed: 0.5 m/s
  • Piston Ø: 25 to 360 mm
  • Piston rod Ø: 16 to 250 mm

Mill Type Cylinder

Mechanical engineering is the field of activity for mill type cylinders. They are accustomed in mobile machinery, civil engineering, steel and iron works, cranes, offshore applications, presses and ship-building. The key feature of mill type cylinders is their robustness.

Key features of the mill-type hydraulic cylinders:

  • Robust design
  • Larger piston diameters
  • High nominal pressure
  • Long stroke length

The top and bottom of a mill type cylinder and the cylinder barrel are screwed, welded or tightly connected with bolts or retaining rings. In comparison to tie-rod cylinders, mill-type cylinders have fewer mounting possibilities, yet, standard mounting, such as flange, clevis, trunnion and foot mounting, are possible.

Typical parameters are:

  • Nominal pressure: up to 350 bar
  • Maximum stroke length: 6,000+ mm
  • Maximum stroke speed: 0.5 m/s
  • Piston Ø: 25 to 450 mm
  • Piston rod Ø: 14 to 220 mm

Servo Cylinder System

Servo cylinder systems are hydraulic cylinders having hydrostatic bearings. Hydrostatic bearings have minimal friction and are perfect in situations where high oscillation frequencies using small amplitudes are required. Such as materials screening devices and motion simulators.

Key features of a servo hydraulic cylinders:

  • Low friction
  • Accuracy
  • High dynamic response
  • High speeds

Servo cylinder systems are accessible with hydrostatic wedge cap bearings or with full hydrostatic bearings that is cavity bearings. The type of bearings you need relies on the required speed of the hydraulic system in operation.

Typical parameters are:

  • Pressure: up to 210 bar (with cavity bearings up to 280 bar)
  • Stroke speed: 2 m/s (up to 4 m/s with cavity bearings)
  • Force: 1 to 4,000 kN (up to 10,000 kN with cavity bearings)

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