Calves should only be delivered by persons with the proper training and expertise. The first thing to find out if it is a normal (head first) presentation and if both forelegs are in the birth canal, then that the calf is small enough for normal delivery, and finally if there is enough lubrication for delivery. Only then can ropes be attached and pulled by the power of two men. On no account should there be excessive force, never using mechanical power. This is cruel, dangerous and illegal, and will lead to prosecution under the Animals Protection Act. If a calving case is difficult or protracted it is better and cost-effective to leave delivery to a trained expert (a veterinarian) who can save both cow and calf if called to assist early enough.
Humane euthanasia must be considered if the calf cannot be delivered.