Hip clamps should not be used to get the cow up if there was a possibility of pelvic damage as a result of calving. So veterinary diagnosis of the cow's prospects is essential before using hip clamps.
If hip clamps are used, they should be used with padding and not so tightly applied that they cause damage to the hips, skin or pelvis. Hip clamps must be removed if the cow makes no attempt at bearing her own weight after 5 minutes.
Slings under the abdomen can be used for longer periods of time in an attempt to help the cow recover. You may need to use the hip clamps to lift the cow to get the sling under her, but make sure the cow in a sling can breathe freely and not suffer any unnecessary discomfort.
A cow must not be suspended in a sling for more than one hour at a time. The longer the cow is down, the less are her chances of recovery. It's an offence to let a cow suffer.