"Powersafe" clutch on BCS

Jens767 · Mar 13, 2016

Hi again again NibbanaFarm

OldMec could easily be right - especially with all the safety-stuff our politicians comes up with these days. Joel also thinks there is a brake function in the PowerSafe clutch. It could be interesting to hear firsthand from someone who have dismantled a clutch, if they found a brake function inside.

When the mowing-season begins, I will try to see if I can also find the sweet spot you mention - sounds interesting.

I can imagine this brake function being annoying when you use the tractor with a sulky or trailer. For an unprepared user it can even be dangerous, and that's probably why BCS has put a leaflet in the user's manual, encouraging users not to use sulkies or trailers.

Officially, you only have 3 gears in either direction on the BCSs with the PowerSafe clutch, as the transport gear has been blocked in the gear quadrant. Have you been able to find the 4th gear on your tractor? That might come in handy, if you use sulkies and trailers a lot.

Best regards

Jens

Maxxjod · Mar 14, 2016

Hi,

The PowerSafe clutch came about due to a change in EU regulations in 2009, some of the key parts of these new regulations are,
1) The engine must not be used as part of the operator presence control(deadmans) system.
2) The machine must have a 2 stage reset after the deadmans lever is released.
3) The machine must stop within 2 seconds of the deadmans lever being released.
4) The machines maximum travel speed was reduced.
5) Machines must not exert a force over a certain amount in neutral on a slope.
So as a result of these changes BCS decided to design a new style of clutch to resolve many of the regulations.

The PowerSafe clutch uses oil pressure to push a piston forwards that then pushes the drive plates together to provide drive, the clutch unit has a small oil pump that produces around 7-8 bar. When the deadmans lever or clutch lever is released the oil is able to bypasses the clutch piston which then releases pressure on the clutch plates, this release of pressure separates the clutch plates and locks them in place inside the clutch housing causing the machine to stop within 2 seconds. There is no separate braking system in side the clutch or gearbox its all done through the PowerSafe clutch unit.

Due to the revised regulations there is no 4th gear due to the speed it produced, the gears for 4th are not in the gearbox so unfortunately its not just a case of modifying the gear selector plate.

It is not a good idea to use the 'sweet spot' to allow the machine to coast as it could cause rapid wear of the metal on metal clutch plates in the PowerSafe clutch unit, the plates are intended to be either engaged or disengaged not dragging in-between.

It is very important that oil changes are carried out on a regular basis to ensure that the clutch unit is free of any contaminates and has the best quality of oil, while the oil may look clean its EP qualities may have degraded, we recommend that gearbox oil and filters are replaced every 6 months.

I have recently been to BCS for my annual factory training and the PowerSafe clutch units being produced now are exactly the same as the ones first produced in 2011, BCS have found no reason to change any of the PowerSafe clutch components due to wear or damage, i think this shows how good the PowerSafe clutch system is.

Regards

Maxxjod

David Cockey · Mar 14, 2016

Can a Powersafe unit be moved without the engine running, or are the wheels and tires prevented from rotating?

NibbanaFarm · Mar 14, 2016

Wow, that was a lot of excellent information. Thanks Maxxjod.

David, the tractors can be moved in neutral, with or without the engine running. With some difficulty. They can't be moved in gear though. At least I can't move mine while in gear.

rickyd79 · Apr 1, 2016

Maxxjod said:
Hi,

The PowerSafe clutch came about due to a change in EU regulations in 2009, some of the key parts of these new regulations are,
1) The engine must not be used as part of the operator presence control(deadmans) system.
2) The machine must have a 2 stage reset after the deadmans lever is released.
3) The machine must stop within 2 seconds of the deadmans lever being released.
4) The machines maximum travel speed was reduced.
5) Machines must not exert a force over a certain amount in neutral on a slope.
So as a result of these changes BCS decided to design a new style of clutch to resolve many of the regulations.

The PowerSafe clutch uses oil pressure to push a piston forwards that then pushes the drive plates together to provide drive, the clutch unit has a small oil pump that produces around 7-8 bar. When the deadmans lever or clutch lever is released the oil is able to bypasses the clutch piston which then releases pressure on the clutch plates, this release of pressure separates the clutch plates and locks them in place inside the clutch housing causing the machine to stop within 2 seconds. There is no separate braking system in side the clutch or gearbox its all done through the PowerSafe clutch unit.

Due to the revised regulations there is no 4th gear due to the speed it produced, the gears for 4th are not in the gearbox so unfortunately its not just a case of modifying the gear selector plate.

It is not a good idea to use the 'sweet spot' to allow the machine to coast as it could cause rapid wear of the metal on metal clutch plates in the PowerSafe clutch unit, the plates are intended to be either engaged or disengaged not dragging in-between.

It is very important that oil changes are carried out on a regular basis to ensure that the clutch unit is free of any contaminates and has the best quality of oil, while the oil may look clean its EP qualities may have degraded, we recommend that gearbox oil and filters are replaced every 6 months.

I have recently been to BCS for my annual factory training and the PowerSafe clutch units being produced now are exactly the same as the ones first produced in 2011, BCS have found no reason to change any of the PowerSafe clutch components due to wear or damage, i think this shows how good the PowerSafe clutch system is.

Regards

Maxxjod

Hi Maxxjob

One question: In regards to "slipping the clutch" or the "sweet spot" as you put it, sometimes I find it necessary to "slip the clutch" in order to get into first gear and or to engage the PTO. Are you of the opinion that the 2-3 seconds this takes may damage the clutch? If so, what do you do to get it into gear when "gears" are not lined up? Of course one could roll the tractor, but who wants to do that...

thanks!

Maxxjod · Apr 1, 2016

Hi Rickyd79,

Using the clutch to 'feel' the gears in is fine, its using the 'sweet spot' to allow the machine to free-wheel with a trailer/sulky on that would cause the issue to the PowerSafe clutch.

Maxxjod

Jens767 · Apr 2, 2016

Hi Maxxjod

Thank you very much for your post - but most of all for sharing your knowledge regarding the PowerSafe clutch with all of us :thumbsup:

If I understand you right, the PowerSafe clutch has an extra feature compared to a more conventional clutch, which is to lock the clutch plates inside the clutch housing when disengaged, causing rotation to stop within 2 seconds. This confirms what a number of members who have had the chance to drive a BCS with the PowerSafe clutch have experienced, and this explains why the 4th transport gear has been blocked/removed, and that the use of sulkies and trailers are no longer permitted. As mentioned on page 10 in this thread, there seems to be a difference in the way the 3 working gears works, compared to the transport gear though.

Best regards

Jens

Maxxjod · Apr 2, 2016

Hi,

The easiest way to explain the PowerSafe clutch to our customers is that it works in reverse to the standard BCS clutch. The original clutches, pre 2011 for UK, used rather large scary springs to provide the drive to the gearbox from the engine. The spring or springs in the clutch pushed the central part of the clutch against the outer part to provide drive, pulling on the clutch lever pushed the inner part of the clutch towards the engine to release the clutch, in the same way an automotive clutch works. Now the issue with this system is that if any external part of the clutch system such as the lever, cable etc is missing or badly damaged the machine will continue to run. On the PowerSafe clutch the springs are replaced with oil pressure and the whole clutch operation is flipped around, this means that if any damage to the cables etc occurs the clutch will not operate leading to a safe condition of the machine.

You may have seen this video before but it does show how the clutch system works-
BCS hydraulic clutch PowerSafe® - YouTube

oldmech · Apr 4, 2016

Hi! In PowerSafe Clutch. They are a brake. I explain! When engine is not running. Clutch is innoperative! You cannot free the transmission input shaft, This one is blocked or braked by four circular springs Parts 56556213 on disks (4) of transmission input shaft ( If you remove these springs no more brake)

When you start engine, Pressure pump go up and you can by a valve add pressure on a circular piston, This one compress the springs(4) free the disks(4) from gear box and add pressure on shaft disks from engine for turns transmisssion input shaft.
The Piston in clutch is one way. The brake action are from springs (automatic)
I think PowerSafe is a good system for safety, But the hydraulic pump takes some power from engine . I dont know How Much?
Good luck Oldmech

Luisella · Apr 10, 2016

NibbanaFarm hi,

I have done two oil changes, once a year at the end of the season. The fluid was clear in my tractor as well, however the magnetic plug was fairly well coated with metallic particles on both ocaisions, perhaps a little less on the second oil change.

Maxxjod hi,

Thanks for that from me as well. Really every six months! did they suggest perhaps six months or x number of hours?

Best regards

Lu