stress control entec ch25

[stevestrees]

just bought an entecCH25. great little machine however no stress control.  can this be fitted or is there simply no space or way of doing it. 

thanks

[openspaceman]

On 03/08/2020 at 21:16, stevestrees said:

just bought an entecCH25. great little machine however no stress control.  can this be fitted or is there simply no space or way of doing it. 

thanks

A deafening silence from the experts probably means this question is a bit too contentious.

 

I suspect compliance is the major issue as chippers can be dangerous and  modifications that are not approved could lead to problems with H&SE if and when something goes wrong. Does the Entec conform to the required hopper and feed chute dimensions and stop controls?

 

 

Mostly it's probably not worth doing, mind I'm speaking as someone who has spent a few hours each day for the last two tending an ancient chipper with no stress control on some leylandii tops and I'd guess 30% of the time was necessary just to prevent jams and stalls which would not have occurred with a modern 6" chipper but then will these modern chippers still be working everyday after 30 years?

[monkeybusiness]

I had one years ago with stress control, so it is doable. There was a little control box that pointed at a toothed wheel on the flywheel rotor shaft above and behind the engine I seem to recall.

[openspaceman]

10 hours ago, monkeybusiness said:

I had one years ago with stress control, so it is doable. There was a little control box that pointed at a toothed wheel on the flywheel rotor shaft above and behind the engine I seem to recall.

That's interesting, I didn't use a timberwolf with stress control until around 2000 after they morphed. It made me realise how much more productive it could be to just stick a piece in and walk away knowing it would cope rather than tend  the Dosko. The Dosko is still going but the loss of productivity over the years must have made keeping it a poor choice. Later I realised the "letter box" opening was of value when chipping conifer tops which would bunch up in the 6" square opening and then  marvelled at the aggressive feed of the Forst 6".

 

So if the parts are available  a retrofit should be okay.

 

Some chippers seem to use the alternator W output for speed sensing so no longer any need for the toothed wheel and hall effect sensor.

 

The first generation of stress control was very simple in that the tachometer sensed rotor speed and switched a solenoid spool in the feed to the main spool such that the hydraulic pressure was all dumped to tank. If the blades were very aggressive they could continue to pull material in by over running the feed motor(s), I don't know how this is managed nowadays whether by blade angle design or using an over centre valve on the output of the main spool to feed motor(s).

 

The hysteresis of the speed controlled switch  meant that high idle had to be reached by the engine before the hydraulic flow to the feed spool was restored. Logically you would cut the feed when the engine fell to the revs for maximum torque, in practice manufacturers seem to cut out and back in nearer to maximum power.

[Husqvarna King]

Had a 98 entec that I only sold a couple of year ago. It had a no stress  unit. When it broke,around 2010 I had it replaced with the same system as the timberwolf 125/150, it only cost 3-400 quid from memory (at prochip) and was still working well when I sold it ?