Slide Control Cables

[cmillsap]

All owners of busses with Prevost slides should be aware that there is a white plastic panel/sheet/guard that Prevost installed along the edge of the slide control cables pack to prevent the cables from rubbing against the outer side of the slide body when extending or retracting the slide (see pic below). That plastic guard is attached to the cable mechanism with cable ties, at least it was on my bus and had become unfastened in two locations and was making a noise as the slide was being moved in and out. If the plastic guard comes loose, it can get crumpled when the cable mechanism is moving. That could do a lot of damage to the cables and jam the mechanism.

With the slide retracted, shining a flashlight down between the slide body and the cabinet behind the driver’s seat will allow you to see the cable mechanism and the plastic guard. If it is loose, it should be repaired or removed.

After the Prevost slide expert at Mira Loma inspected the issue and described the reason for its being there, I opted to just have them remove it as the potential scuffing of the slide paint is very minimal if the cables happen to touch the side of the slide during the in & out motion.

[davidbrady]

Good discovery Chuck. I think those are affectionately known as the YoYo strings. They're used as linear tracking devices to keep the slide from getting wedged.

[Hisham Amaral]

Why would Prevost service remove a tracking cable if Prevost engineering add that cable to track the slide movement? Are there other tracking devices to do the slide progress?

[cmillsap]

(03-27-2018 09:13)davidbrady Wrote:  Good discovery Chuck. I think those are affectionately known as the YoYo strings. They're used as linear tracking devices to keep the slide from getting wedged.

David, Hish,

I don't know much about how these slides operate but as I understand it there are 4 slide motors (actually gear boxes) tied to the main electric motor. they are located at each corner of the slide room. I think the yoyo strings tie each of the 4 slide motors (gear boxes) together with the main motor to keep them in sync with each other as they drive the slide in and out on individual racks.

The cables that I am referring to are the slide's power cables. They are located on the floor beside the front side of the slide room (packed) in a mechanism that allows them to follow the slide as it moves in and out. As the slide is extended this mechanism follows the slide out and deposits the cables into the cabinet behind the driver's seat. When the slide is retracting this mechanism carries the cables from the cabinet and follows the slide in. In other words, this mechanism just rolls up or unrolls the cables as the slide room moves in or out. So, there is never any slack in the cables.

The plastic piece that we removed was just put there to prevent the cable carring mechanism from possibly touching the slide body during travel. It has no function other than that.

[CC_Guy]

Chuck,

Based on your description and the picture of the part removed, I have to wonder if you have Prevost slides. I can tell you a Prevost slide does not have any power that goes into the slide. Any power cables would be installed by the converter in the way they see fit. I know Marathon uses Valid slides along with Prevost slides. Could this be a Valid slide?

The Yo-Yo is located on the rear lower side of a front slide. And yes, it tells the controller when to stop indicating an all the way in or all the way out position. FWIW, these were done away with in newer slides, Gen-4 I think.

A Prevost slide that has the side pins has a single motor that drives a 90 degree gear that attaches to a dual shaft 90 degree gear that drives the lower horizontal shaft. That same 90 degree gear box that drives the lower horizontal shaft drives a vertical shaft that attaches to a like 90 degree gear box. This gear box drives the upper horizontal shaft.

I probably know these slides better than most given few have ever changed one of the 2 90 degree gear boxes.

[cmillsap]

(03-27-2018 18:11)CC_Guy Wrote:  Chuck,

Based on your description and the picture of the part removed, I have to wonder if you have Prevost slides. I can tell you a Prevost slide does not have any power that goes into the slide. Any power cables would be installed by the converter in the way they see fit. I know Marathon uses Valid slides along with Prevost slides. Could this be a Valid slide?

The Yo-Yo is located on the rear lower side of a front slide. And yes, it tells the controller when to stop indicating an all the way in or all the way out position. FWIW, these were done away with in newer slides, Gen-4 I think.

A Prevost slide that has the side pins has a single motor that drives a 90 degree gear that attaches to a dual shaft 90 degree gear that drives the lower horizontal shaft. That same 90 degree gear box that drives the lower horizontal shaft drives a vertical shaft that attaches to a like 90 degree gear box. This gear box drives the upper horizontal shaft.

I probably know these slides better than most given few have ever changed one of the 2 90 degree gear boxes.

Hello CC Guy,

Nice to hear from you again. Thank you for the better description of the 4 gear boxes located at each corner of the slide room and how they work. I do have the single slide motor that powers the 4 gearboxes back and forth on their individual racks as I described (altho poorly) above. It is located high up in driver's side bay #3. I do have a 4 pin Prevost slide.

Now the question is: What is the mechanism with the cables inside that is located on the front side of the slide body and follows the slide movement? I presumed (wrongly maybe) they were power cables but they may not be powered? The Prevost slide expert explained that the mechanism has cables inside it. These cables are rolled up into the cabinet behind the driver's seat as the slide is extended. I should have watched more closely as the 2 Techs worked to remove the plastic guard but it's close quarters and I didn't want to get in their way. They were fortunate to get the guard remove without having to disassemble and remove the cabinetry for better access.

Perhaps David is correct that this mechanism is the yoyo. It may have been installed on the front side of the slide rather than the rear side as you mentioned where it is usually located?

The reason we removed the plastic guard is because it was damaged and loose. The Prevost slide expert was concerned that it could get crumpled thereby damaging the cables causing the slide to fail to function. BTY, he said the earlier model Prevost slides did not have the plastic guard installed.

My purpose for posting the issue here was to inform others to inspect their Prevost slide to make sure they do not have the same problem.

[CC_Guy]

Hmmm,

A Prevost front slide of your coach's era should have 6 pins, 4 are structural. The 2 shaft drive gear boxes are solely on the rear directly above the slide motor.

Attached is the upper rear of the front slide. The bottom has the same gear box. FYI, the picture should be rotated 90 degrees clockwise.

[cmillsap]

(03-28-2018 15:57)CC_Guy Wrote:  Hmmm,

A Prevost front slide of your coach's era should have 6 pins, 4 are structural. The 2 shaft drive gear boxes are solely on the rear directly above the slide motor.

Attached is the upper rear of the front slide. The bottom has the same gear box. FYI, the picture should be rotated 90 degrees clockwise.

Thanks, CC Guy, Appreciate the pic. I read your post where you rebuilt your slide a while back. Big job! Not many would undertake it.

Yeah, there are 6 pins (not 4) on my slide
I guess I shouda went out and counted the pin receiver holes as I forgot about the center pins.

Regarding the mechanism with the cables inside located on the forward side of the slide, I will call the Prevost slide guru and ask him to explain exactly what that is and what its function is.

[davidbrady]

Now we know what a mechanical engineer's solution to a slide drive mechanism looks like. An electrical engineer's solution is two or more direct drive synchronized motors.