GMN >> Freewheel Clutches > Products > Rollerramp clutches > Technology

Technology

Design

Rollerramp clutches have 4 main components:

• The concentric and round raceway of the outer ring
• The star-shaped configuration of the clamping ramps at the inner ring
• The clamping rollers
• Separate spring loading for each roller, based at the inner ring

Below the maximum speed shown in the data sheets, the rollers are ready for instant torque pick-up, as soon as the sense of rotation changes.

Some relative motion between inner and outer ring will be physically necessary for transmitting 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. The angle of twist may not be called slippage or intermittent slippage.

Indexing

Design efficiency is enhanced when the outer ring is the driving component, oscillating back and forth. At intermittent rotation of the inner ring, motion can be made almost continuous by mounting clutches side by side with overlapping actuation. Increased spring force can be supplied for very high indexing requirements. The use of light weight oils and the addition of a second clutch for backstopping will improve efficiency.

The above mentioned necessity of some elastic deformation, resulting in a certain angle of twist, has to be taken into consideration to find the best ratio of nominal torque to applied torque.

Overrunning

Overrunning clutches achieve maximum performance when the inner ring is the slower or stationary part.

Backstop

Backstops operate best when the outer ring is held stationary allowing the inner ring to rotate freely in one direction. The use of low viscosity lubricants is important. For very high speeds where RPM exceeds catalog ratings we often suggest circulating oil systems. Consult GMN when in doubt.

Torque capacity series VS / VSNU / VF/ VGF / VGL / VGLP

The nominal torque M, shown in the data sheets, refers to 107 cycles. It is calculated with a service factor of S = 2.5. Torque peaks in use may never be higher than M x 2.5 [Nm].

Torque capacity series VGV

The nominal torque M, shown in the data sheets, refers to 105 cycles. It does not include any service factors. Torque peaks in use may never be higher than nominal torque.

Torque capacity series VEK

In general the nominal torque M, shown in the data sheets, refers to 107 cycles and it is also calculated with a service factor of S = 2.5. Please note also that at series VEK torque peaks referring to the inertia of all accelerated parts have to be expected.

For proper disengagement a minimum of driven mass will be required depending on the speed. Within the limits, shown in the data sheets (n_max; n_min;), the inertia of the VEK clutch itself will be sufficient for proper disengagement (n_min) and reasonable lifetime (n_max).

Bolt - tightening torque

For high-strength bolts DIN 912

Bolts	Class 8	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 diameter