Manlift rolled down hill.....won't go now!!

[flobbest]

First post here guys, here's my problem.

I have a 1997 Simon Trailblazer manlift (now Terex) that I bought used. It's 4 wheel drive but the front wheels were not driving when I bought it so I just assumed the hydramotors were toast. There was a LOT of water in the hydraulic fluid which I changed before running the lift. It got around just fine on the rear drive motor (looks like you pros call em travel motors) and I used it for about a year that way.

I brought it home from a job (it drove up on the trailer just fine) unloaded it in my side yard which has a barely noticable slope to it. When I looked out the window the next morning, I was shocked to see that the lift was gone! Well to my astonishiment, it had rolled through the yard (driveway) and down a pretty go sized hill. It rolled about 60-70 yards I would guess. I was able to move it on level ground but it would not go up hill. Now it won't go at all. The wheels just move a bit but that's it. All the other functions are operational. I did change the high pressure filter with no effect (it looked great).

So here's my question or questions rather:

Would that roll down the hill take out my travel motor? Does that seem reasonable?

What should I do next? The drain test? There are only two lines on the motor, does it matter which one I pull and plug for drain test?

Should I pull it off and dissasemble the motor? Whould I be able to tell visually what the problem is?

Thanks for any help....take care.

Frank

 

[barklee]

First post here guys, here's my problem.

I have a 1997 Simon Trailblazer manlift (now Terex) that I bought used. It's 4 wheel drive but the front wheels were not driving when I bought it so I just assumed the hydramotors were toast. There was a LOT of water in the hydraulic fluid which I changed before running the lift. It got around just fine on the rear drive motor (looks like you pros call em travel motors) and I used it for about a year that way.

I brought it home from a job (it drove up on the trailer just fine) unloaded it in my side yard which has a barely noticable slope to it. When I looked out the window the next morning, I was shocked to see that the lift was gone! Well to my astonishiment, it had rolled through the yard (driveway) and down a pretty go sized hill. It rolled about 60-70 yards I would guess. I was able to move it on level ground but it would not go up hill. Now it won't go at all. The wheels just move a bit but that's it. All the other functions are operational. I did change the high pressure filter with no effect (it looked great).

So here's my question or questions rather:

Would that roll down the hill take out my travel motor? Does that seem reasonable?

What should I do next? The drain test? There are only two lines on the motor, does it matter which one I pull and plug for drain test?

Should I pull it off and dissasemble the motor? Whould I be able to tell visually what the problem is?

Thanks for any help....take care.

Frank

Let me start by saying you have my condolences! That is something that hits a guy straight in the balls when he sees that.
My guess would be that with the machine rolling that distance there is some damage. I would pull the covers off the hubs and see if all the gears are still in tact. Also, a way to really isolate the damage would be to pull the hydraulic motors out of the back of the hubs. Wire them up out of the way and have another person engage the drive. This would tell you whether the hubs or motors are causing the problems. Maybe do it one at a time..... with the hope that only one wheel is damaged. Then you could go further to determine how to repair the problems. Bare in mind that it is getting extremely difficult to get Terex lift parts. I still have a TB110 and getting seal kits for the hubs or drive motors is nearly impossible. I had to have all the seals matched up at a local supplier. Hopefully you have hubs from a manufacturer that is still in business, Terex used several different companies through the years.

 

[willie59]

I seem to be having a great deal of difficulty getting the Genie website working tonight to get a look at the Trailblazer parts manuals, don't know what's up with that. But to continue this discussion and possible solution, do you have a Trailblazer 40, 50, or 60?

An incident like this with an aerial lift is troublesome, what if you had a man in the platform at the time this thing took a ride? I once had to work on a JLG 80HX that took a free ride down a steep slope with a man in the basket. I never got to talk to the operator, but given the scene when I got to the machine, I can with confidence say that man was scared out of his mind before that thing came to a stop.

Before you put a man back in that platform, you need to go through the drive system in general, the brakes in particular, which is where I'm having difficulty viewing those parts pages for some reason, so as to offer some advice.

I can only say what I had to do on that JLG, which may be a more aggressive approach than what you may do as once I start working on a customer owned machine that has been involved in a free wheel event, then everything I touch, I assume legal liability. First, I disassembled the planetary hubs to check them, then checked the shaft that connects drive motor to planetary hub. Once I determined there was no failure with those components, all that was left was the brake assembly and drive motors. The brake units, I didn't fool around with them, again, I assume liability, so I chose to rebuild them with new plates/disks and new springs. As for the drive motors, I sent them to a pump/motor shop to have them gone through.

Aerial lifts carry with them a high degree of liability because they carry a man in a platform. An event like this makes it incumbent on the machine owner to make certain all components involved with drive and brakes are in proper order, it's just the nature of the beast your working with.

 

[barklee]

There is a yoke that connects the hub shaft to the drive motor isnt there?

 

[willie59]

That's where it sucks not being able to view parts pages barklee. From what little I could see on the Trailblaser 40, one axle has drive motors, was never able to identify brakes on that axle. The other axle was "differential" type axle with a drive motor connected by a "yoke". Was not able to identify a brake on that axle either before I said "to heck with it" and closed out the Genie parts pages. Since I can't view the machine pages, I can't say with certainty about this particular machine, but most all aerial lifts that I've worked on has positive brake application, meaning, when machine is not in use, engine not running, brakes are applied without input from an operator. When not in motion or operation, brakes are on. Which troubles me on this incident, machine rolled overnight with no input from an operator. Something is bad wrong here, and I can only imagine if this event would have happened with an operator in the platform.

 

[flobbest]

First off, thank you willie and barklee for your very informative responses.

It is a Trailblazer 40.

Yes, there is a yoke between the rear drive motor and the hub shaft.

I have the manuals (parts and service) and from what I can glean from the drawings, there are hydraulicly actuated disc brakes on the rear axle. One on either side of the differential with seperate "fail safe" actuators. It looks to me as though both brakes would have to have failed for this animal to roll??

Please bear in mind that I am an electrician (retired), not a heavy equipment mechanic. Also, this machine is sitting in my back yard and I am limited to hand tools and a floor jack. I'm not even sure if I could jack up one wheel. As far as pulling the hubs, axle, brakes, well, I could try but this stuff is pretty rusty. Not sure if I could even get my channel locks on the bolts.....that's a joke but seriously this looks like pretty heavy duty stuff for me.

I have a friend that wants to buy the thing so I thought I would try and get it going first but this sounds pretty serious. It's possible we're talking scrape iron here. I runs great (diesel) but if I'm looking at thousands to repair I doubt if it's worth it?

I'll have to ponder this a bit. You guys are awesome and I appreciate the help. I will report back here what I decide to do. Thanks again.

Frank

 

[willie59]

It's going to be difficult for me to advise you on this one flobbest as I have never worked on one of these. But if you are going to sell this to a friend, without repairing problem first, you are going to have to advise him about this event. Otherwise, if it were to roll and injure or kill either him or someone else, that would be on your conscience, I could not live with that myself.

From what I can tell by the parts pages, the differential axle contains the brakes for the unit, there may be brakes on the motors on the steer axle, can't tell for sure yet. Regardless, the brakes on the diff axle are supposed to brake the machine when it's at rest, it takes hyd pressure, as in moving drive joystick, to "release" the brakes. Once you release drive joystick, or when machine is at rest, springs apply the brakes.

There are two brake units, one on each side of the differential, for the two wheels on the differential axle. You could have severely worn brake disks, which is really not likely as these machines don't move fast enough to wear out brake disks, but it's always a possibility. Looking at the parts breakdown, there are several things that could cause the brakes to not hold on a slope, I'll mention a couple things that could be possible, but there's no way I can say for certain where the problem is, that would be brakes are not adjusted properly, adjusting nut #97, or broken Belleville washers #94, a problem with either of these would cause brakes to not hold on a slope. If it were me I'd be removing that housing #99 and inspecting these components. Hope this helps.

 

[flobbest]

Willie, you are absoluty right, selling this thing like this would be like selling a gun with a defective safety. Not going to happen.

I find it puzzling.....wouldn't both brakes have to fail to allow it to roll strait down the hill? If only one brake failed, seems like it would just turn a bit. Perhaps only one brake was funtional before and then the second one failed. I'll see if I can get those actuators apart and see what I can see. Thanks again.

Frank

 

[flobbest]

Had a chance to mess around with the lift today (roll away event). Jacked up the rear axle (that's where the brakes are) and ran the the travel motor. Now this is a 4 wheel drive but the front wheel motors do not work. Elevated, the rear axle turns fine, stop and the brakes seem to be working. Next, I operated the machine through my yard (nice trenches) and up a sizable hill, actually it's a 10% grade (drops 3' in 30'). When I let off the drive control,it slowly rolls, more like creeps back down the hill. When I get down to about a 1-2% grade the brakes will hold it. I have no idea what grade the brakes should hold at but I would like to think they should lock up the wheels and skid before rolling but as I say, I have no idea.

I see from the manual that there is an adjustment procedure and will try that when I get time. Will check back with results. May be a couple of weeks as I am leaving town for a week.

Frank

 

[barklee]

Had a chance to mess around with the lift today (roll away event). Jacked up the rear axle (that's where the brakes are) and ran the the travel motor. Now this is a 4 wheel drive but the front wheel motors do not work. Elevated, the rear axle turns fine, stop and the brakes seem to be working. Next, I operated the machine through my yard (nice trenches) and up a sizable hill, actually it's a 10% grade (drops 3' in 30'). When I let off the drive control,it slowly rolls, more like creeps back down the hill. When I get down to about a 1-2% grade the brakes will hold it. I have no idea what grade the brakes should hold at but I would like to think they should lock up the wheels and skid before rolling but as I say, I have no idea.

I see from the manual that there is an adjustment procedure and will try that when I get time. Will check back with results. May be a couple of weeks as I am leaving town for a week.

Frank

I believe these brakes will actually hold a 50% grade or until tipping. I know we have an old tag trailer that has at least a 40% grade and the lifts do not roll back. At one time we had a Condor that would roll right back down if you let off the controls.

 

[flobbest]

barklee, thanks for the input. That does confirm my suspicion that the brakes should be holding better than they are. I"ll take a stab at adjusting them when I return from the Florida keys. Leaving tomorrow just in time for the hurricane!! Will post back resutls of brake adjust.

On another topic about my lift....the engine......mine is an Isuzu diesel. There are several engine options in my manual (with drawings) but no Isuzu? It definatly looks like a factory install. Is this an odd ball engine for this?? Thanks.

Frank