Valves ensure consistent cut of rubber blanks

Hydraulic components from Parker Hannifin enable Barwell, maker of ram extruders, to cut the time and cost of setting up and programming these dedicated machines to user specification.

Ram extruders produce rubber blanks and preforms such as seals and O-rings mainly for the car industry. Hydraulic ram force and oil flow are critical to product quality. Stephen Grocott, Barwell chief engineer, says Parker proportional valves make machine-setting simpler. Valves control the delivery of oil to the hydraulic ram and knife, which extrudes liquid rubber into a die and then cuts blanks to size.

Parker valves are linear rather than sinusoidal, making it easier to calculate voltage to set the valve spool to control oil flow and pressure to get a constant weight of rubber blank.

Parker pumps deliver hot liquid rubber to the machines. By monitoring changes in upstream and downstream loads, sensors ensure the pressure differential across the valves is correct.

As rubber is elastic and affected by temperature its behaviour is unpredictable, which puts special demands on pumped system design where there is a need to deliver a constant quality end product.

Machine pneumatics are also supplied by Parker.


A rustling canopy of rainforest foliage and jungle beasts made lifelike by compressed air, set the scene at a new London eatery.

Two Cyclon 105 compressors installed at the Rainforest Cafe in Shaftesbury Avenue supply ultra-dry air at 1,450bar to 12 animatrons, including a tiger, crocodile, gorillas, elephants, butterflies and some smaller animals. Real parrots, a huge tank of marine fish and sound effects complete the fantasy.

Silent rotary screw air compressors work alternately for even wear and backup during maintenance. Distributor Motivair designed and installed the pneumatics.


Compressor-maker Ecoair UK continues its assault on the 15 30kW market with a range of air-cooled single stage rotary screw machines said to be efficient and require little maintenance.

The A20 and A40 compressors use Ecoair’s latest Power Drive automatic belt (power band) tensioning system instead of springs. New springs cause bounce on startup and belts to stretch; worn springs cause belt slippage. Sixteen models provide outputs from 1.39 to 4.46m3/min at pressures from 7 13bar.