I work in a warehouse accepting deliveries from trucks.  Occasionally the delivery drivers ask if we have a pallet truck that they can use so they can move pallets from one side of the truck to the other (there is only access to one side of the truck for our fork lift)  Are we ok to allow use of our pallet truck by a non employee of the business? - just thinking, if there was an accident when lifting the pallet truck onto the lorry or when the lorry driver is using the pallet truck - where would we stand then? 

Thanks for any advice.

You could look at insisting they arrive with their own pallet truck.

Personally though I would look at re-designing your delivery point to eliminate all manual handling and work at height in what I presume to be a single open curtain side (after all if the driver injures themselves and is taken to hospital you will be stuck with their vehicle blocking your yard).

Never mind getting the pallet tuck on to the bed of the vehicle how does the driver gain access?

Liability started when they drove in to the yard.