Roller Ramp Clutches

GMN Roller Ramp Clutches

Roller Ramp clutches are mainly used in heavy duty applications that require durability in a clutch.

Our VS, VSNU and VF series must be used inside housings because they aren’t self supporting and require outside bearing support to ensure operational alignment of the inner and outer ring. When using this series, take extra precautions to avoid axial misalignment and thrust loads.

Our VGF and VGL series doesn’t require external housing and can be bolted straight to a wall (or other stabilizing structure) with the shaft mounted and held in place with the inner ring keyway of the roller ramp clutch.

Roller Ramp Clutch 101

A Roller Ramp Clutch has four main components:

1. The round outer ring
2. The clamping rollers
3. The star-like clamping ramps (located at the inner ring)
4. Spring loading for each individual roller (located at the inner ring)

As long as the rollers are operated at or below their max speed, they are ready for instant torque pick-up as soon as they sense a change in rotation.

Some relative motion between inner and outer ring will be necessary in order to transmit full torque due to the elastic deformation of all components involved. The relation between applied torque and the angle of twist will be linear and constant under constant operating conditions.

Roller Ramp Product Line Series Overview

The VS, VSNU and VF Roller Ramp Series

Our VS, VSNU and VF series must be used inside housings because they aren’t self supporting and require outside bearing support to ensure operational alignment of the inner and outer ring. When using this series, take extra precautions to avoid axial misalignment and thrust loads.

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The VGF, VGV, VGL(P) and VEK Roller Ramp Series

The VGF series has bearing support. Sleeve bushings are used for VGF 8 to VGF 20 products and VGF 25 to VGF 60 uses ball bearing support.

The VGV series has a torque arm (lever arm) which is good for indexing and backstopping. Sleeve bushings support this series and these clutches are double sealed by the sleeve bushings.

The VGL & VGLP series doesn’t require external housing and can be bolted straight to a wall (or other stabilizing structure) with the shaft mounted and held in place with the inner ring key way of the roller ramp clutch.

Our VEK series is capable of multiple revolutions. When the pawl hits stop, the rollers are disengaged separating the driving parts. When the pawl is released again, driving members are connected instantly.

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Design Technology of the Roller Ramp Clutch

Indexing

Indexing can best be defined as the transformation of forward and backward movement into rotational irregular motion, like in material feeding.

When indexing roller ramp clutches, design the outer ring to be the driving component, oscillating back and forth, with intermittent rotation of the inner ring. This will boost the effectiveness of indexing.

If the roller ramp clutches are mounted side-by-side with overlapping actuation, a continuous motion is almost made.

For very high indexing requirements, increased spring force can be applied. Improve efficiency by adding a second backstopping clutch and using light weight oils .

Make sure to find the best ratio of nominal torque to applied torque and account for the angle of twist that results from elastic deformation in the example above.

A few examples of indexing clutch applications: Printing, Textile and Sewing Machines, Packaging, Agricultural Machines and more.

Overrunning

When you need an overrunning clutch, you can achieve maximum performance by designing a stationary inner ring or making it the slowest part of your clutch.

A few examples of overrunning clutch applications: Starter Units, Auxiliary Drives, Auxiliary Power Equipment, Conveyors, Turbines, Bakery and Cutlery Equipment.

Backstopping

Backstopping performs the best when you hold the outer ring stationary and allow the inner ring to rotate free in one direction.

The use of low viscosity lubricants is important for backstopping. If you have high speeds that exceed catalog RPM standards, we recommend a circulating oil system for backstopping. Make sure to contact us for more details on this.

A few examples of backstopping clutch applications: Winches, Cranes, Elevators, Gearboxes, Pumps, Ventilators and Power Plant Equipment.

Transmittable Torque

For our GMN roller ramp clutch series VS / VSNU / VF/ VGF / VGL / VGLP / VEK the nominal torque (M) refers to 107 cycles. It’s calculated with a service factor of S = 2.5. Torque peaks in use may never be higher than M x 2.5 [Nm]. Please note: Series VEK torque peaks is referring to the inertia of all accelerated parts and has to be expected.

For our GMN roller ramp clutch series VGV the nominal torque (M) refers to 105 cycles and doesn’t include any service factors. Torque peaks in use may never be higher than nominal torque.

To properly disengage, a minimum of driven mass will be required depending on the speed. Within the limits of nmax and nmin (please refer to the specific data sheets for this information) the inertia of the VEK clutch itself will be sufficient for proper disengagement (nmin) and reasonable lifetime (nmax).

Bolts – Torque Indicating Wrench

Bolts	Class B	Class 9	Series	Series
Type	Tightening Torque [NM]		VGL, VGLP	VEK
M4	3, 5	4	–	10
M5	7	8, 5	12, 15	15, 20
M6	12, 5	14, 5	20, 25, 30, 35	30
M8	30	35	40, 45, 50	40
M10	60	70	55, 60, 70, 80	50
M12	105	120

Thread length in outer ring: L = 1.5 x Bolt Type