Trailer breakaway cable

[Refueler]

Would it allow me to use the handbrake to stop, if not control, the trailer when backing it down a launching ramp by hand? If not, no point at all.

My vans with Auto-reverse ... as long as I was using the handbrake from stationary and easing it off to manually control it backwards - yes the handbrake worked. BUT if I had moved the van first THEN tried using the handbrake - then auto-reverse actioned and hand brake needed to be pulled on hard .... to try and bring shoes back to braking ...
As far as I can see and tell from the videos . read on line ... the energy store makes no difference to this .. I may be wrong - but as say - look at the earlier video and also diagrams online ... you see the over-centre action .....

I wonder if as the guy says - it has immensely powerful spring - whether that firing may cause auto-reverse action to cancel as in my hard full on use of handbrake ?

If it was me - I would go to a van dealers / trailer site and chat to them about it ...

 

[JumbleDuck]

If it was me - I would go to a van dealers / trailer site and chat to them about it ...

Good idea. There is an Ifor Williams place nearby - I'll try them when normality returns.

 

[Mudisox]

Ivor williams know most , and are good. I always used to disengage the auto brake system when trying to reverse. I thought that I was more in control when manoeuvring at very slow speed and the whole rig would not do its' own thing.

 

[KREW2]

Would it allow me to use the handbrake to stop, if not control, the trailer when backing it down a launching ramp by hand? If not, no point at all.

For control. No, is the short answer. Once the energy store is over the centre it takes muscles like Garth to stop it going all the way, which "should" stop the trailer in its tracks.
Then you will have to release it which takes a lot of grunt.

I'm assuming your handbrake works going forwards, but you would not be able to leave the loaded trailer, unhitched on a slope, without it rolling back. If so you have fitted them correctly, and should you want to park unhitched on a slope you should have an energy store.

Here is how to set up for parking an unhitched trailer with Knott breaks.
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The perfect handbrake action should be that the handbrake gently applies itself having lifted approximately 100mm once applied. When in the ‘on’ position, the shaft of the handle should be vertical.
If the trailer is now pushed backwards whilst the handbrake is applied then the handle should move into the vertical auto reverse position. You must be very careful at this point to ensure that you trip all brake drums into auto reverse. If the handle is not fully 90degrees then this would suggest that not all the drums are tripped out. Should this happen, you would need to take the handbrake off, pull the trailer forward then reapply the handbrake and attempt to roll the trailer backwards.

 

[Refueler]

Time to call it quits I think ..... OP has a all the info he needs ... later has been answered and dare I say it suggested to speak to a dealer to get the definitive answer.