The type of mounting for a hydraulic cylinder is chosen by answering two questions: how the load moves during the cycle and along which direction the force must be transferred to the structure.
If the load moves along a fixed axis, the correct mounting is rigid (flange, feet, threaded holes). If the machine kinematics impose an angular variation, the mounting must be articulated (clevis, spherical bearing, trunnions).
The ISO 6020/2 standard codifies all these solutions. Conforti's CD/DK/MD series tie-rod hydraulic cylinders offer standardized mountings in the catalogue: front and rear flanges (ME5/ME6), female and male clevises and ball-jointed eye (MP1/MP3/MP5), front, rear and intermediate trunnions (MT1/MT2/MT4), feet (MS2), threaded holes and extended tie-rods (MX5/MX6, MX1/MX2/MX3). The mounting determines how loads are distributed over rod, guide and seals, and it enters the buckling check through the stroke factor.
The cylinder only works well with axial loads
The rod of a hydraulic cylinder is designed to transmit force along its own axis. Any radial force introduced by a misalignment between the cylinder axis and the load path, or by a mounting inconsistent with the kinematics, is transferred to the guide bushing and the rod seals, accelerating their wear. The type of mounting is the tool with which the designer controls this aspect: a rigid mounting constrains the cylinder to work exactly along the intended axis, while an articulated mounting allows it to follow the load when it is the machine that imposes the oscillation. Choosing a non-optimal mounting means creating a problem that is difficult to compensate for.
Fixed or oscillating: the machine kinematics decide
The first selection criterion is the path of the point where the force is applied. If the angle between cylinder and load does not change during the cycle (a vertical press, a pusher on guides), the mounting is rigid and the choice shifts to where the force should be transferred (front head, rear head or side feet). If instead the load rotates around a fulcrum (an articulated arm, a tipper, a tilting table), the cylinder must be able to oscillate: the mounting is articulated and the plane (or planes) of oscillation must be chosen. It is a multi-parameter assessment, not a sequence: load direction, kinematics, available space and stroke must be considered together, because each one rules out some solutions and favours others.
Rigid mountings: flanges, feet, threaded holes, extended tie-rods
For fixed installations the CD/DK/MD series provide four families, all to ISO 6020/2. The ME5 front flange and the ME6 rear flange fix the cylinder to a wall or a plate on the plane of the head: they are the reference solution when the force must be transferred in line with the axis, and the position, front or rear, is chosen according to the machine geometry and to how the structure receives the load. MS2 feet support the cylinder on a plane parallel to its axis: a simple and accessible solution, with the caveat that the thrust axis does not lie on the mounting plane, so the foot screws must be checked for the resulting stresses. The MX5 front and MX6 rear threaded holes and the MX1/MX2/MX3 extended tie-rods use elements already present in the cylinder for mounting through plates and panels, reducing overall dimensions and additional components.
Articulated mountings: clevises, spherical bearing, trunnions
When the kinematics require oscillation, the catalogue offers two families. The rear mountings, female clevis MP1, male clevis MP3 and ball-jointed eye MP5, let the cylinder oscillate around a pin on the rear head: MP1 and MP3 work on a defined plane of oscillation, while MP5, thanks to its spherical bearing, also compensates for out-of-plane misalignments and is the prudent choice when the actual path is not perfectly contained in one plane. The MT1 (front), MT2 (rear) and MT4 (intermediate) trunnions move the oscillation axis along the cylinder body: the MT4 intermediate trunnions, in particular, make it possible to position the fulcrum where the machine requires it (the position is specified in the order with dimension XV). The choice of mounting must always be coordinated with the rod end: for an oscillating cylinder the catalogue provides rod-end accessories with spherical bearing or clevis with pin, because articulation at only one end would leave residual radial loads on the rod.
Mounting and buckling: how they are really connected
The buckling resistance of a cylinder under thrust depends on the rod, in particular on its diameter in relation to its free length. Each mounting has its own stroke factor FC. The stroke multiplied by FC gives the ideal length LI, on which the maximum thrust that can be exerted for each rod diameter depends (see the diagram in the Conforti catalogue). In practice: for the same stroke and thrust, an oscillating mounting may require a larger rod than a well-constrained rigid mounting. That is why the buckling check must be carried out after choosing the mounting family, not before. It is one of the reasons why mounting, rod and stroke are decided together.
The typical mistake: rigid mounting where the kinematics oscillate
The most frequent mistake is not choosing the "wrong" mounting between two equivalent ones: it is rigidly mounting a cylinder that the machine wants to let oscillate. A rigid mounting on a path that deviates by even a few degrees loads rod and bushing radially at every cycle; the cylinder works, but it wears out guides and seals much earlier than expected, with leaks and unplanned downtime. The mirror case is more subtle: specifying articulation on a single plane (MP1/MP3) when the actual oscillation or misalignment is not always on that plane. In that case the correct answer is the MP5 ball-jointed eye, possibly with a spherical rod-end accessory on the rod side as well. A practical rule for the design review: if you cannot demonstrate that the cylinder axis and the load path coincide at every point of the stroke, the mounting must provide at least one degree of freedom.
Selection matrix for ISO 6020/2 mountings in the Conforti catalogue, CD/DK/MD series
Mounting | Constraint | Application | Notes |
Front flange ME5 (A) · Rear flange ME6 (B) | Rigid, on a wall/plate perpendicular to the axis | Load along a fixed axis, force transferred in line to the structure (e.g. presses, guided pushers) | Front or rear position depending on the machine geometry and on the point where the structure receives the load |
Feet MS2 (E) | Rigid, on a plane parallel to the axis | Fixed installations resting on a base, with easy access | The thrust axis does not lie on the mounting plane: check the foot screws for the resulting stresses |
Threaded holes MX5/MX6 · Extended tie-rods MX1 (Q), MX2 (S), MX3 (R) | Rigid, through plates or panels | Compact mounting in plate structures, without additional elements | They use the cylinder's own holes and tie-rods: check plate thickness and interface |
Female clevis MP1 (M) · Male clevis MP3 (C) | Articulated, oscillation on a defined plane | Load rotating around a fulcrum with a path contained in a plane perpendicular to the clevis axis (arms, levers, tippers) | Coordinate with an articulated rod-end accessory (clevis with pin); out-of-plane misalignments are not compensated |
Ball-jointed eye MP5 (D) | Articulated, with compensation of out-of-plane misalignments (spherical bearing) | Oscillating kinematics in which the actual path is not perfectly contained in the plane perpendicular to the pivot axis | Prudent choice in doubtful cases; LD accessory available in the catalogue; combine with a spherical rod-end accessory on the rod side |
Front trunnions MT1 · rear MT2 · intermediate MT4 (H) | Articulated, oscillation fulcrum along the body | When the fulcrum must be at a precise point of the cylinder body (overall dimensions, mass balancing) | For MT4 the fulcrum position is specified in the order with dimension XV (min/max in the catalogue for each bore) |
Applications
The choice of mounting weighs differently depending on the context. In presses and guided thrust units, the load is axial and fixed: ME5/ME6 flanges or MS2 feet, with the buckling check favoured by the rigid layout. In industrial automation and special machines, fixed-axis actuation and articulated kinematics coexist in the same plant: this is the typical case in which the matrix above avoids the mistake of standardizing the mounting "to keep the bill of materials simple" where the paths are different. In die-casting and in plants with constrained space, MT4 intermediate trunnions allow the fulcrum to be placed where space permits, and plate mountings (MX) reduce the number of components involved. On long strokes (test benches, extended handling), the choice of mounting is intertwined with the construction choice: the HD/HK counterflange configuration, recommended by the catalogue above 2000 mm of stroke, retains the same ISO mounting layouts as the tie-rod range.
The Conforti solution
All the mountings described are standardized catalogue options, selectable at the configuration stage.
CD/DK/MD series — ISO 6020/2 tie-rod cylinders
The CD/DK/MD ISO 6020/2 tie-rod series (bores 25–200 mm, operating pressure 160 bar) offer in the catalogue the full range of standardized mountings (flanges, clevises, ball joint, trunnions, feet, plate mountings) plus rod-end accessories with spherical bearing or clevis: the configuration consistent with the machine kinematics is built while staying within the standard, with available spare parts and every cylinder tested to ISO 10100.
HD/HK series — ISO 6020/2 counterflange cylinders
For long strokes and operating pressures up to 210 bar, the HD/HK ISO 6020/2 counterflange series (bores 50–200 mm) retain the overall dimensions and mounting layouts of the standard while eliminating very long tie-rods: the choice of mounting stays the same, only the construction changes.