Posts Tagged ‘Quick Release Valves’

The Ins and Outs of the Industrial Clutch Combination QRV/Rotary Union

Thursday, April 30th, 2015

The Industrial Clutch combination Rotary Seal & QRV (Quick Release/Exhaust Valve) offers the ability to tune the clutch engagement to meet each presses unique requirements. The Industrial Rotary Seal & QRV is a modular design to fit the complete range of Industrial Clutches used on mechanical stamping presses and many Verson clutches.  The Poppets are a standard part across all configurations with adjustable orifices and there are various cap’s providing several air inlet options.

Industrial Clutch Combination QRV/Rotary Union

Industrial Clutch Combination QRV/Rotary Union

Integrating the QRV into the Rotary Union allows am Industrial Clutch the unique ability to more rapidly exhaust the clutch to reduce “Overlap” with the brake setting during the press stopping, than any other approach.  This operational feature significantly improves press operation by reducing heat in the clutch and brake, while limiting unnecessary wear on the friction material and other parts.

In addition, the poppet orifice diameter can be adjusted by drilling them to a different diameter.  The poppet orifice controls the engagement of the clutch, the smaller the orifice the slower the clutch engages and conversely, the larger the orifice the quicker the clutch engages.  Proper orifice size improves press operation by reducing “Overlap” with the brake when the press is started and providing a smoother clutch engagement.  Under proper guidance, the orifice tuning can be customized to each specific press, providing optimum performance.  The standard for Industrial Clutches is:

Industrial Clutch Orfice Sizes

The operating principle is simple in concept, but often misunderstood, leading to most operating issues.

  • When the clutch is engaged, the supply pressure is higher than the pressure in the clutch, the pressure differential moves the poppet in the rotary union to block the exhaust port while the orifice meters the air to the clutch:
Industrial Clutch Engaging

Industrial Clutch Engaging

  • When the clutch is disengaged, the clutch pressure is higher than the supply pressure, the pressure differential moves the poppet in the rotary union to open the exhaust port:
Industrial Clutch Exhausting

Industrial Clutch Exhausting

A common issue Torque Inc., witnesses, on customer presses, is the QRV is not operating properly.  This issue is caused by the supply pressure from the press safety valve not falling fast enough relative to the clutch pressure when the clutch disengages to create the pressure differential to move the poppet.  There are two primary causes of this:

  1. The poppet orifice is drilled too large, allowing the clutch pressure to exhaust through the orifices at the same rate the supply pressure drops.
  2. The pneumatic plumbing and press safety valve are not allowing the supply pressure to drop fast enough for the QRV to react. The typical installation with this issue has the press safety valve located next to the brake with a very long line to the clutch. With a single press safety valve, the brake exhaust going through the valve prevents the clutch supply line pressure from dropping quickly enough for the QRV to move.

When working with the Industrial Clutch combination Rotary Seal & QRV, a simple check is to feel the exhaust air rushing out of the unit immediately upon the clutch releasing at the end of a stroke.

Torque Inc., Sales Engineers are available to consult with any Torque Inc., customers with questions or issues with these units.  We have the expertise to assist tuning your press for optimal clutch engagement and disengagement.  Please contact us with any concerns, we are happy to be of service.


Quick Release Valves (QRV’s)

Tuesday, June 14th, 2011

Most industrial Air Clutch/Brake applications have Quick Release Valves (QRV or Quick Exhaust) engineered into the air system to provide rapid exhaust of the air pressure by providing a large exhaust port right at the clutch or brake.  Air systems with properly engineered, installed and maintained QRV’s,  offer significantly improved operation of clutches and brakes in high cycle applications (single stroke operation of a press).

To properly engineer, install or maintain a system with QRV’s,  it’s important to understand what they are and how they work.  The most popular QRV’s supplied by Torque Incorporated are:

Quick Exhaust

Wichita QRV - Quick Release Valve (Quick Exhaust)

Industrial QRV

Industrial Clutch QRV - Rotary Seal

The Wichita QRV’s are engineered to mount to the Airtube Spuds to provide rapid exhaust from the Wichita Clutch/Brake.  The Industrial Clutch QRV – Rotary Seal is engineered to mount to the Cylinder of an Industrial LK Clutch (and Verson clutches) to provide rapid exhaust and controlled clutch engagement by modifying the orifices in the poppet assembly.

Quick Release Valve (QRV or Quick Exhaust) operation is fairly easy to understand, the basic schematic using a Quick Release Valve (QRV or Quick Exhaust) is below:

QRV Basic Schematic in Clutch/Brake Air System

QRV Basic Schematic in Clutch/Brake Air System

When the 3/2 valve is engaged to pressurize the clutch/brake, the air pressure at P1 is greater than the air pressure at P2 causing the poppet in the QRV to close the exhaust port, allowing air to flow from the supply to the clutch/brake.  When the 3/2 valve is released, removing pressure from the Clutch/Brake, the air pressure P1 is less than the air pressure P2 causing the poppet in the QRV to seal off the input.  This allows the the air to exhaust the clutch/brake directly through the QRV.

While the operation of QRV’s is very simple,  we see many issues with their application and installation.

  • When QRV’s are installed it is critical that the volume of air between the 3/2 valve and QRV is small enough so P1 remains significantly lower than P2 until the clutch/brake is fully exhausted.
  • QRV’s should never be installed in series.
  • QRV’s are typically only used on Clutches in Stamping Press applications when a separate clutch and brake are used.

QRV’s have wearing parts, their operation should be checked regularly as part of your Preventative Maintenance Program or if you experience erratic stopping or an increase in stop time.  Checking operation can be accomplished by simply cycling the air system and monitoring the QRV to ensure there is a strong puff of air when the system should exhaust.  If the QRV does not respond with a strong blast of exhaust, it should be replaced or rebuilt depending on style.

It is best to run QRV’s without mufflers, if possible, the mufflers tend to slow the exhaust and trap air system contaminates in the QRV.  If you need to abate the noise created by the QRV, use a muffler with a large surface area to not restrict the exhaust flow.

Your Torque Inc. local Sales Engineer is an expert with QRV’s and is available to help you with any issues with your clutch/brake air system design, installation, operation and maintenance.  If you have any questions give us a call, we are happy to be of service.