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SExcessive Braking Effect

Hi, one more issue I'm having!

 

Using Arc Pro my cars come to an abrupt stop as soon as I remove my finger from the controller trigger. There is no freewheeling at all like with my older analogue cars. This 'braking effect' negates any need to use the brake button (which now only seems necessary for pit stops). 

 

This braking effect is so strong that you have to keep a little pressure on the trigger non-stop or the cars immediately halt. This has resulted in cars flying into the back of other cars which have come to an unintended dead stop in front of them.

 

Anyone with similar experiences?

Andy P.

1531 posts


Community Moderator

Are you in digital or analog mode (I am assuming digital because of you mentioning "rear-ending")?

What type of cars are they?

What brand what year?

Are you racing with magnets?

Dr_C

271 posts

Malcolm is raising great questions, it will be interesting to learn more about how the ARC PRO applies braking... should we assume there is some form of dynamic braking designed into the ARC PRO firmware? Unless someone is able to share an answer... let's investigate further...

 

C

woodcote

635 posts

These are great questions! From using ARC Pro and ARC Air, I am also assuming some form of dynamic braking - a small reverse current going to the motor when the trigger is released.

 

The brake button itself is an on/off switch, as in the previous Scalextric Sport Digital systems. However, from a peek in the communication protocols, it does look like there's scope for more varied braking responses - possibly with ARC compatible Slot.it controllers that have adjustable braking. It would be good if this switched off dynamic braking.

 

I do use the brake button with cars that I've removed the magnets from - just a very quick blip at the end of a straight. There's a sense that there is some dynamic braking with standard non-mag cars, but for cars with traction magnets and cars with high-torque motors (like the Sierra I built here) they do stop quite sharpish.

 

I find it a challenge to roll cars with magnets round my R1 hairpin - partly because they stop when I release the trigger and partly because there's little 'tail-out' drift - and I do find myself needing to keep some throttle through R2 esses. It's a different way of driving to the non-magnet cars. The Sierra really is tricky to drive, in part I need to learn to drive competely differently with the extra torque, but I presume my difficulties are compounded by the dynamic braking. Keeping a little throttle going does definitely help.

 

Malcolm - are you running cars with the traction magnets in them? And what cars are you using? Some are a bit more stuck down than others! For example, the BTCC Civics are rather more grippy than the MGs, VWs and BMW 125s as their traction magnets sit much closer to the rails on the track. All modern cars are very different beasts compared to the old Scalextric cars that had no magnets or much weaker ceramic magnets.

Pault86

36 posts

I made a post with pictures but it will take a day to come up.

 

Braking must be done by the chip, right? I know the pb can send a zero throttle signal down the rails to a particular car ID. Does the chip use that to short the motor, thereby causing braking? In the ARC PRO, is dynamic braking always enabled?

 

In the c7002 controller, pushing the brake button used to switch in an 18k ohm resistor the pb could sense to know to turn braking on. In the wireless controller the brake button appears to be just a switch whose state is read by the controller's logic board. 

 

In any event, once baking is activated - at either zero throttle or by brake button - the factors that affect braking are the motor and the gear ratio. Using an armature with more copper wound on it, using stronger magnets in the motor, or increasing the power angle - the point in the rotation of an armature at which a coil becomes energized - will all increase braking. The gear ratio effects braking because the faster the motor must turn while operating as a generator the greater the current flowing in the braking circuit. A car with 4:1 gearing - 4 turns of the pinion for each turn of the crown - will have more brakes than a car with 3:1 gearing, other factors equal.

 

Regardless of how SSD implements braking, once it is turned on only the car, itself, should influence how strong the braking effect is. 

Pault86

36 posts

Been a long time, but I think we have a brake bit in the data sent down the rails, the chip would use that, not the throttle level, to initiate braking. Have to recall the data on the rails format.

Dr_C

271 posts

Agree there is a brake bit in the data sent to the cars and that this is enabled by the power base when the brake button is pressed (both with SSD wired and wireless throttles). However, with the original C7030 6 car power base there was also the option of dynamic braking. Then, with SSDC there was/is the option of progressive braking which I understand rapidly toggles this brake bit. So the question remains... what is happening with the ARC PRO that causes the excessive braking effect reported by malcolm_garett...? is some form of dynamic braking implemented in the ARC PRO (i.e. setting of the brake bit automatically when easing off the throttle) or is it simply the effect of strong magnets causing rapid deceleration?

C

@woodcote

Cheers everyone again, for your responses!

Malcolm - are you running cars with the traction magnets in them? And what cars are you using? 

 

I have only four digital cars at present: 

Two Ford Escort Mk1s (C3635 and 3592)

Two MGB's (C3270A and C3631)

All have 'reduced magnets' in them (I have snipped the ends off the regular bar magnets and glued them in their original position). There was a similar harsh braking effect before snipping the magnets, but I can't say that I have detected a significant change. 

It might be worth mentioning that the Digital Plugs are all brand new, coming direct from Hornby in a new batch (they were out of stock until March). The new plugs look different from the ones previously pictured on the Scalextric website, Amazon etc. which had a large cylindrical part on them, which is now absent. Maybe there is a difference / differences between them?

BTW do ideas and suggestions from this forun get considered when the App development team meet?

And if / when the App gets updated are there / will there be notifications here / elsewhere as to which issues have been addressed.

Thanks again everyone!

Pault86

36 posts

Yes, how does actually ARC PRO implement and control braking? I don't see any way to turn it on and off as in the c7042 APB. As the figures show, dynamic braking is usually achieved by shorting the motor when you completely lift off the hand controller. A resistor in series with the motor when it is shorted can reduce the braking effect, this is not shown in the figures.

 

Andy P.

1531 posts


Community Moderator

BTW do ideas and suggestions from this forun get considered when the App development team meet?

And if / when the App gets updated are there / will there be notifications here / elsewhere as to which issues have been addressed.

Yes one of the things I do constantly is funnel feedback to the respectvie parties.

There will always be an annoucment in the ARC forum when a new version arrives...

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