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Operating the punch press PRK-2

Categories: Drive shaft repair

Features of the PRK-2 screw press

Transfer mechanism

To operate a driveshaft punch press, it seems, that you don’t need to know about any components of the press. But it can make a difference, especially if one of the two similar machines does its work better than the other.

The first thing to start with is a description of its transmission mechanism. The conversion of rotary motion into translational motion is done through means of a ball screw. This mechanism was not chosen as a transmission mechanism in vain. It has efficiency of 95 % and it’s not so little, for comparison a screw with trapezoidal thread has 30-35 % of efficiency, and if with greasing it is as much as 40 %. That’s it, to recreate the same efforts as created by the ballscrew, with a trapezoidal screw you would spend three times as much effort. Thanks to the ballscrew on the press PRK-2 using only muscle power can create a force of 5500 kg.

Only rack and pinion drives can compete with ballscrews in terms of performance. But only in terms of performance. The thing is that for the punching process it is important to feel how the process goes. Any locksmith will agree that there is no tool more accurate than a man’s hand. The ballscrew works without backlash, allowing the locksmith to feel the forces in the pressing and punching process with his hands. There is no play in the ball screw as there is in the rack. Also, the ball screw requires no maintenance, unlike the rack.

Overall dimensions

Given the fact that the repair of driveshafts, as a rule,  not necessary happens in aircraft hangars, but in the rooms a little smaller. Designers have taken care of that the press PRK-2 does not occupy a large area and at the same time has a fairly large work area. By the way, the working area is so large that you will never feel discomfort while working. The press easily accommodates in the working area even a fixture for core and crosshead assembly.

Structural rigidity

Just looking at the photo of the press PRK-2 you can do without words, but since we are describing it. It is worth paying attention to the thickness of metal of which all the press power elements are made and all the most dangerous places are strengthened by “braids” and “ribs”. With such a design, the press PRK-2 could absorb loads several times greater than its actual ones.

Application range of the PRK-2 press

The first thing it needs to be said is that the press is quite versatile. Its area of application is much more than just maintaining driveshafts. You can operate the driveshaft punch press in any repair shop. We use it for applications such as assembling spindles and pressing bearings and bushings. Even the presses we are talking about are made with this press. As for the repair of driveshafts, you will be available for such operations as:

  1. Disassembly of crosses and other elements of the driveshaft.
  2. Assembly of the crosses, outboard bearings and other assemblies.
  3. Punching of unassembled car and trucks crosses.


By using the disassembly press, you at least reduce the risk of cracks in the “ears” of the driveshaft “fork”, as there are no shock loads. The disassembly process is neat, which means you can save on components and valerian.

Assembly of crosses, outboard bearings and spline pairs

There is no secret to the fact that the assembly of any assembly or joint should proceed without misalignment. This is especially important when assembling crosses. Crosses are finicky, and if you misalign them even slightly during assembly, it can cause the cross arm to jam during operation or, more likely, rapid wear of the joint due to excessive friction and temperature. The danger of a misalignment is that in this case the seating hole in the “fork of the driveshaft” is deformed, which means that you will have to rebuild the surface or even replace the fork in order to reassemble it without misalignment.

It is not a problem to eliminate the possibility of misalignment during the assembly of the cross shaft, you just need to have such a device as a “clamp” at hand.

Bracket for the assembly and punching of crosses

The design of the bracket solves several problems that can arise during the assembly of the joint. Firstly, as mentioned above, the “bracket” eliminates the possibility of misalignment when assembling the cross arm. This is due to the “guide hole” through which the “fixture stop” moves and the “heel” which is mounted at the bottom of the “bracket”. By pressing the “heel” which has a recess with the size of the bearing hole of the driveshaft fork, the spider takes the correct position relative to the “stop”, and then it is a small thing, holding the cup to press it smoothly into the hole to the desired depth.

The second problem that arises during assembly is the deformation of the “ear” of the driveshaft under the action of the press. If this occurs, the alignment of the holes in the “driveshaft yoke” is disturbed, which can add problems to the assembly or even make it impossible. In addition, if there are internal stresses in the metal of the fork or a defect is present, cracks or microcracks may occur when deforming the “ear”, which is more dangerous.

In order to eliminate the possibility of deformation of the driveshaft’s “ear” the “bracket” is equipped with a “foot”. This is a stop that limits the possibility of deflection of the “ear” when pressing the “cup”. Two types of “feet” are included in the delivery set with the “bracket” and this is enough to work with most common driveshafts.

Punching of unassembled crosses

In both assembly and punching, misalignment is unacceptable. In the case of a punching operation, misalignment can cause damage to the “stacking punch” with which the operation is carried out. Additionally, by distorting the “stacking punch”, the mount on the “crosshead cup” may be loosened, which can cause destruction of the joint when the driveshaft is in operation.

A “bracket” is also used to solve the problem of a skewed “stacking punch”.

“Stacking punches” come in a variety of types:

  • with two teeth;
  • with three teeth;
  • with six teeth.

Two-tooth stacking punch” is usually used to repair steering gimbals or very small gimbals.

The most common “stacking punches” are the six-toothed ones. With these, it is possible to punch at once without turning the punch. For three-toothed punches a 180-degree turn is necessary and for this in the “staple”, the “stop” has the ability to rotate. Why use three-toothed punches at all? The answer is simple, with three-toothed punches it’s easier to core a press, that creates less force. If you have a rack and pinion press, you would be better off using 3 or 4 tooth punches.

“Stacking punches” like any other tool have their durability period, which means that they are a consumable item. If necessary, you can order them from our company.

Quantity of presses in the workshop

A common mistake in a repair shop is to have and operate only one driveshaft punch press. When a shop is just opening, one press is usually enough. But as the order grows, the press can become a bottleneck in the shop. When all the workers are in line for the press. Our experience shows that with about 60 – 70 cards per month enough to one press. For every other 60 – 70 it is desirable to have another press. Ie if you want to do 200 shafts in a month, plan a place under 3 presses. They don’t have to be the same you can buy a P1515 as a second press. But we recommend not to create a bottleneck from the press right away.

If you have any questions about how to operate the driveshaft punch press or need advice on expanding the equipment fleet of the repair shop, please contact us for guidance.