Gear change RPM

[jenevers]

I notice that the manual states that engine/gearbox interlocking speed and reversing controls ( which I haven't got) only drops the RPM to 770 before allowing gear change.

I've always, manually, gone down to tick over before going from ahead to astern which can't be bad.

I rarely cruise above 900rpm anyway! So I suppose technically, I only need to knock a few revs off.

Think I'll stick to my old habit however. But........interesting all the same.

[RLWP]

There are lots of scary things about old engines if you follow their original specifications

 

Idle speeds on HA/HB engines for instance

 

Richard

[jenevers]

There are lots of scary things about old engines if you follow their original specifications

 

Idle speeds on HA/HB engines for instance

 

Richard

Well ........go on and elaborate!

[RLWP]

Can't find the book...

 

From memory an HA idle speed is around 600rpm, and HB is higher than that. Many of these engines are installed and adjusted to idle slower than that. If you run them at the proper idle speed, most owners are convinced they will damage the gearbox because it's so fast

 

Richard

[jenevers]

Yes I must admit 770rpm sounds fast to be changing gear!

[martyn 1]

Yes I must admit 770rpm sounds fast to be changing gear!

In vintage engine terms yes that is the best part of half revs or even getting onto two thirds but in modern terms its slow. So for example if your engine was fitted with a PRM,ZF or Twindisc gearbox then 770 wouldn't be an issue as most modern engines idle near that anyway. for example the Scania DI13 marine engines I work with most days with the day job can be set to idle anywhere between 550 and 800 and the same goes for the V10 MTU's in some of our other boats.

[alan_fincher]

Can't find the book...

 

From memory an HA idle speed is around 600rpm, and HB is higher than that. Many of these engines are installed and adjusted to idle slower than that. If you run them at the proper idle speed, most owners are convinced they will damage the gearbox because it's so fast

 

Richard

 

If Sickle were idling at 600 RPM, I wouldn't half upset a lot of the "please pass on tickover" brigade, if I were to follow their instruction to the letter!

[jenevers]

In vintage engine terms yes that is the best part of half revs or even getting onto two thirds but in modern terms its slow. So for example if your engine was fitted with a PRM,ZF or Twindisc gearbox then 770 wouldn't be an issue as most modern engines idle near that anyway. for example the Scania DI13 marine engines I work with most days with the day job can be set to idle anywhere between 550 and 800 and the same goes for the V10 MTU's in some of our other boats.

 

I've got a Gardner 2UC so it would appear it's OK to change at 770rpm...........but I'm not going to!