The DAF 85 CF is a lovely motor, nice and easy to drive, comfortable inside too ! Nice truck !
The “dog” is the tensioner - its got two hooks, one at each end, a kind of mechanism between them, and a handle about a foot long. Its really hard to explain how to operate one but your mate will show you.
If you use the “dog”, instead of the ratchet, use a hollow scaffold pole as an extension bar and close the mechanism at arm’s length, away from your face. Health & Safety will frown upon you if you use the extension bar as you’re supposed to close the handle by hand, yet you can never get the tension required without it.
When the handle is closed, it will lie in parallel with the mechanism, hooks and chains - you’ll see how it works when you use it tomorrow. Watch out if the handle is slightly bent as it doesn’t lie parallel with the rest. A bent handle has a habit of springing open under tension so keep your face well away, a straight handle won’t. The handles get bent because drivers use scaffold poles on them ! Catch 22 I know !
It happened when I first started driving HGV, 15 years ago. I was moving 11 concrete test blocks weighing 2 tonnes each. One of the chains came loose so I stopped, got on the trailer and re-tightened it. It was dark (0400 hrs mid-winter) so I took a closer look to make sure it had closed properly and BANG !!! You know the rest.
Throw your chains over your load and under the trailer’s chassis rails. Don’t attach your chains to the hooks under the edge of the trailer (used for roping and sheeting) as they’re not strong enough. I’ve seen drivers chain 22 tonne loads using these hooks which are only tack-welded on. If they ever lost their load they’ve only got themselves to blame.
Tension the chains whilst standing on the ground, not on the trailer. A month prior to the other accident, I was on top of a dozen or so steel piles, chaining them onto the trailer, about 12 feet off the ground. One minute I was on the trailer, the next minute I was in a warm hospital bed - I had been there for four days unconscious. I still can’t remember falling off the trailer. A totally surreal experience !