Comparing Locking Devices (Part1)

We start telling you what this article is not about and this explanation will suffice also for others more that will surely follow in the future on the Blog Vega Hydraulic Cylinders. The purpose of today’s article is not to speculate on the quality, or selling price of products concurrent of Vega’s, but simply to give some tech-commercial insight useful while promoting Vega Hydraulic Cylinders.

We would like to compare 4 different Mechanical Locking technologies popular on Plastic Mold Injection market. After having very briefly explained how the Locking Systems work we will compare the overall dimensions and locking power. We are confident at the end of the article you will be able to make your own opinion.

Kindly note that all data collected and presented here, including drawings comes from the official catalogues of 4 different companies.

The first product we are going to consider is manufactured by a French company named HPS and the product code is HRBN.

In the initial stage of the stroke movement, oil will flow and push the piston forward. When the piston arrives and the end cylinder stroke, locking segments are pushed inside the groove sited in the frontward position and with the help of the floating piston the ring is locked. At this point the rod is locked until oil flows front the other side.

Here you can see a simple drawing with segment in both position, locking on top and released on bottom.

HPS HRBN Lock Cylinder

The second product on our list is VZS251 Locking Cylinder produced by HEB Hydraulik Elementebau GmbH. The operating principle of the HEB locking cylinders consists of positive mechanical locking of the extended piston rod at the full limit of its stroke by means of special locking and securing elements. This yields a theoretically rigid connecting element. Naturally, the individual moving parts, manufacturing tolerances and elasticity of the cylinder rod and locking mechanism cause the loaded cylinder to have a certain amount of elastic resilience under load.

Here is the second drawing with highlighted in red the locking mechanism.

HEB VZS251 Lock Cylinder

The third Locking Device we will compare is CyPull from Cytec Systems, and the operative description is as follows:

All CyPull locking core pull cylinders work basically according to double acting cylinders whose piston rod is extended by applying hydraulic pressure. When the final position of the piston rod is reached the locking slide moves in converse direction and presses the locking segments into the annular groove of the piston rod. So the segments are fixed in radial and axial position. That means: the piston rod is positively locked. The hydraulic pressure can be switched off.

Here is another drawing with clearly marked the locking system.

CyPull Cytec

Now we are going to talk about Vega Locking Cylinder and I still refer to our catalogue. The V260CF are double-acting hydraulic cylinders with a mechanical locking system of the rod in the end stroke position (extended rod), which permits to contrast very high opposite thrusts. Such a solution is widely applicable in the field of plastic injection and die-casting molds, in order to stand the injection pressure on large molding surfaces. The rod is hydraulically unlocked automatically when the piston comes back.

Please refer to the following video to see Vega V260CF Lock Cylinder in operation:

Now we can compare the 4 Hydraulic Lock Cylinders by selecting 1 fix parameter, namely the locking force requested by a hypothetical customer. Our customer needs to lock 25000 daN, and he wants to choose the correct Bore Size and Overall dimension for all 4 models strong enough to uphold this opposing force generated by the injection mold slide.

The following chart is able to highlight the important values necessary to select the most convenient Hydraulic Lock Cylinder for the specifications given customer.

Compare Locking Devices

          *Values expressed in mm



  1. sashibhusan das

    Require positive locking cylinder .
    Contact person detail.

    • Vega Blogger

      Dear Sir,
      you can contact Miss. Tartaro at email address: Kind regards

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