Presses with a lower drive work properly as long as they are able to transmit motion to the upper roller and the platen. To achieve this, it is necessary to knurl the lower roller (making it rough), so that the roller “grips” the platen, pulling it along and preventing it from slipping. When the platen moves, the upper roller rotates along with it.
Typically, due to continuous friction, the knurling on the lower roller wears down—that is, it becomes smooth. The platen itself also suffers significant wear from constant friction, and as a result, the roller no longer grips the platen properly, causing it to slip. Consequently, artists are forced to apply higher pressure so the matrix prints correctly on the paper, which alters the print because the pressure is modified to prevent roller slippage rather than for the needs of the print itself.
When printing is usually done with low pressure, this slippage does not occur, and the knurling can last many more years. However, over time, this wear will inevitably happen.
With a press that has an upper drive, this problem is completely eliminated. The upper roller is directly connected to the gearbox, which is connected to the wheel, so it is the roller that turns. The rotation of the upper roller moves the platen, and consequently, the lower roller also moves. With this type of press, you can work at low pressure without any concern because the roller will never slip. Of course, it is also possible to work at very high pressures since no component wears down.
Interestingly, some manufacturers have designed presses with a rack and pinion to act directly on the platen to ensure its movement. This method, besides being very expensive, is not entirely satisfactory, as the platen moves in “micro-steps” (due to the teeth engaging and disengaging), and this irregularity is noticeable in the print.
So why are there so many presses with a lower drive on the market? The answer is simple: technically, they are much easier to manufacture. In an upper-drive press, the entire mechanism must follow the movement of the roller (up and down), whereas in a lower-drive press, the rotation mechanism is always fixed.
From this, it follows that an upper-drive press will be more expensive than a lower-drive press.
All of our Cameron and TC model presses are made with an upper-roller drive. You can consult our catalog at https://torculosribes.es/en/presses-torculos-ribes/
We hope this brief technical explanation has been of interest to you. What do you think? Which type of drive do you use? Share your opinion in the comments!
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