This International Standard defines dimensions and specifies performance and safety requirements for traction aid winches used in forestry for assisting supported machines while going uphill and downhill (pulling and braking). It is applicable to fixed and detachable winches and their components, connections and communications, which are used with mobile and self-propelled forestry machinery as defined in ISO 6814 such as harvesters, forwarders, skidders, planting machines, machines for forest ground preparation and machines for extracting residual waste. It is also applicable to remote traction aid winch systems which are installed on a position away from the supported machine. It is not applicable to winches which are not using a controlled rope force while going downhill and winches used for skidding, hoisting operations on cranes, draglines, high lead logging, rope logging systems or yarding. This standard is intended to be applied to traction aid systems used on machines, where without use of these systems the machine would remain stationary on slopes under its independent control (see Appendix D). Forestry machines, as defined in ISO 6814 that are used as anchor or supported machines, are not in the scope of this standard. For guidance refer to EN ISO 11850.