Plant Trailer - Bobcat

[dazzler]

Hi all,

I am setting out on another trailer build for my tracked skid steer business. This one will allow the skidder to be carried behind the 4wd and through the use of a "beaver" tail that will hopefully allow the skidder to unload and load without ramps. I say hopefully as the design will allow a small pair of ramps to swing off the tail if it proves too difficult to do.

Here is a jpg image of the plans;
72802
and one showing how the machine sits on the trailer (imagine people :wink:)
72804
and a sketchup link;
72800
The spring hangers are to be fixed at the junction of the side rails and crossmembers. The side rails are 100x50x2mm duragal and the crossmembers are 50x50x2mm duragal. The skidder will sit on the crossrails, with a few yet to be determined short rails to assist in weight distribution, and this will in effect leave a 50mm lip on the edge of the trailer to stop the skidder sliding off. (normal chains will be used as well)

Tyres are 185/14LT and it will be fitted with electric 10" brakes to the front axle with a handbrake. Axles will be 100mm drop axles if I can get them otherwise 50mm ones. This drops the deck height without altering the spring to chassis gap.

Drawbar at this stage will come out 986mm past the front and is from 75x50x3mm steel. Havent confirmed this yet and the length may change.

Plan of attack at this stage is;

1. Cut side rails to length and a cut 315mm from the tail almost all the way through so that once it is almost complete I can bend the beaver tail down to the right angle and height above the ground, then repair the resulting gap in the rail. I will tack weld the top of the cut so that the rail doesnt drop before I am ready to bend it. Fit drawbar (conditional on being happy on the length. Still havent quite worked this one out yet, see pic;
72803
Suspension is by tandem rocker springs;
72801

2. Cut crossrails and weld to siderails so the underside is flush leaving a 50mm lip. Cut and weld in additional lengthwise inner rails to support machine and some crosswise 'noggins' as well.

3. Fit up spring hangers, fit springs and axles and wheels/tyres.

4. Put car stands under all four corners and using ramps put skidder on trailer. This will allow me to recheck the balance (see load balance of machine on plan) and bend the beaver tail down to the right angle.
Weld in securing points for dog chains.

5. Weld up beaver tail, paint, run electrics and finish off.

Main questions before I start are the beaver tail, just how to do this and also the length of the drawbar. Is the important thing;

a. length of drawbar from FRONT of trailer or
b. length of trailer from middle of front axle to front tip of drawbar

I am thinking b is the correct answer in which case it doesnt really matter how long the drawbar is provided that as you 'jackknife' the trailer the body doesnt hit the tow vehicle. Thoughts?

cheers

dazzler

[Yonnee]

I have some thoughts and comments...

I'll expand when I get home.

[dazzler]

I'll expand when I get home.

Not too expanded I hope, unless you is wearing track pants :p

Oh, and all advice appreciated ;)

[Yonnee]

Not too expanded I hope, unless you is wearing track pants :p

Eeewww... I think.

[dazzler]

Also have to consider what drop for the axles. 2 to 4"

Axle size (D)
Axle beam profile
Stub axle size / profile (mm)
Axle carrying capacity (kg)
Machining profile
Drop height (H) mm / inches
Length (L/W)
45mm
Square
45mm round
1450 kg
Slimline
65mm (2 1/2")
75mm (3")
90mm (3 1/2")
100mm (4")

That look like this;

72896

Just trying to think how low the axle will be to the ground running 14" tyres. From memory you need a minimum clearance under a vehicle of 100mm so I imagine that provided the radius of the tyre is greater than 100mm clearance plus 100mm drop = 200mm radius or 400mm diameter I should be right.

Best draw a picture;

72901

Also need to source QUALITY shackle pins and brackets. Last lot left me a little cold.

Also need to check the axle location. I found the skid steer centre of balance by driving onto a 2 x 4 and found where it rocked. Should this be where the suspension rocker arm is located?

Oh, and what about using overide brakes like these instead of electric?

72911

[Yonnee]

quote=dazzler Hi all,

I am setting out on another trailer build for my tracked skid steer business. This one will allow the skidder to be carried behind the 4wd and through the use of a "beaver" tail that will hopefully allow the skidder to unload and load without ramps. I say hopefully as the design will allow a small pair of ramps to swing off the tail if it proves too difficult to do.

The spring hangers are to be fixed at the junction of the side rails and crossmembers. Not really necessary, more so the position of the suspension should be determined by weight distribution. The location of the cross rails is usually determined by the length of the sheet going on top, ie, on a join. The side rails are 100x50x2mm duragal and the crossmembers are 50x50x2mm duragal. The skidder will sit on the crossrails, I would look at narrowing the 300mm gap between the outer and inner chassis rails, placing the inner rails in line with the centreline (track) of the skidder's wheels. That way it doesn't matter where the cross rails are, or what position the skidder sits on the trailer (fore/aft), or how thick the floor plate is (if used). with a few yet to be determined short rails to assist in weight distribution, and this will in effect leave a 50mm lip on the edge of the trailer to stop the skidder sliding off. (normal chains will be used as well)

Tyres are 185/14LT and it will be fitted with electric 10" brakes to the front axle with a handbrake. Axles will be 100mm drop axles if I can get them otherwise 50mm ones. This drops the deck height without altering the spring to chassis gap. Yes, you can get a 4" drop axle for your application. What's the weight you're aiming for? Trailer? Skidder?
Even if you're not over the 2000kg GVM mark, get your rear axle setup with the mounts for Electric Brakes, as it's alot easier to add them to the rear axle if the mounts are already there. Just bolt up the brake assemblies, swap the hubs for drums, and extend and join up the wiring, and voila, 3200kg of braking instead of 1600kg. And then it's easy to add Breakaway too.

Drawbar at this stage will come out 986mm past the front LONGER!! The widest tow vehicle can be 8' wide, so a minimum 4' (1220mm) drawbar will stop the body of the trailer from hitting any tow vehicle in either a tight turn, or reversing. And the longer the drawbar is on a trailer, the easier it is to reverse. and is from 75x50x3mm steel. Havent confirmed this yet and the length may change.

Plan of attack at this stage is;

1. Cut side rails to length and a cut 315mm from the tail almost all the way through I would cut a wedge from the bottom. That way you're welding a join rather than having to fill a gap. so that once it is almost complete I can bend the beaver tail down to the right angle and height above the ground, then repair the resulting gap in the rail. I will tack weld the top of the cut so that the rail doesnt drop before I am ready to bend it. Fit drawbar (conditional on being happy on the length. Still havent quite worked this one out yet.

Suspension is by tandem rocker springs; Great for load sharing if you're right on the limit of the carrying capacity of the axles, but Rocker springs put alot more load on the towing vehicle. Any weight forward of the centre of the spring set is transfered onto the towbar. This can cause the tow vehicle to wallow, particularly on a vehicle with softer suspension such as a 4WD. If you like, I can calculate the appropriate capacities for Slipper springs, as they require a safety margin. Slippers are simple as there's two moving parts, less to maintain.


2. Cut Front and Rear crossrails and weld to siderails so the underside is flush leaving a 50mm lip. Cut and weld in additional lengthwise inner rails I would do this second, as one piece rails. to support machine and then add your centre cross rails, then some crosswise 'noggins' up the outside as well.

3. Fit up spring hangers, fit springs and axles and wheels/tyres.

4. Put car stands under all four corners and using ramps put skidder on trailer. This will allow me to recheck the balance (see load balance of machine on plan) and bend the beaver tail down to the right angle.
Weld in securing points for dog chains.

5. Weld up beaver tail, paint, run electrics and finish off.

Main questions before I start are the beaver tail, just how to do this and also the length of the drawbar. Is the important thing;

a. length of drawbar from FRONT of trailer or
b. length of trailer from middle of front axle to front tip of drawbar

I am thinking b is the correct answer in which case it doesnt really matter how long the drawbar is provided that as you 'jackknife' the trailer the body doesnt hit the tow vehicle. Thoughts?

cheers

dazzler

[dazzler]

Thanks Yonnee

Great tips. I will print it off so I can read while away this week.

Any negatives on slipper springs?

Skidder is 1450kg. Leaves 550kg for weight of trailer. Big trailer i built weighs 640kg so should make that weight easy. So all up will be just under 2000kg I imagine. Will definately set it up for dual brakes just in case :2tsup:

Appreciate slipper spring rates :)

Not having any tread plate/ floor. Just a few rails for it to sit on and let the mud fall through. :wink:

Dont think im rude if i dont reply, will be away until sunday night but will jump on when able to.

[Yonnee]

quote=dazzlerAlso have to consider what drop for the axles. 2 to 4"

Axle size (D)
Axle beam profile
Stub axle size / profile (mm)
Axle carrying capacity (kg)
Machining profile
Drop height (H) mm / inches
Length (L/W)
45mm
Square
45mm round
1450 kg
Slimline
65mm (2 1/2")
75mm (3")
90mm (3 1/2")
100mm (4")

For a little extra peace of mind and strength, I'd look at:
50mm square axle, slimline bearings, Electric Brakes, and 4" drop.


Just trying to think how low the axle will be to the ground running 14" tyres. From memory you need a minimum clearance under a vehicle of 100mm so I imagine that provided the radius of the tyre is greater than 100mm clearance plus 100mm drop = 200mm radius or 400mm diameter I should be right.
You need to allow for the spring under the axle too, and then the U-bolts. The problem is when you get a flat, the U-bolts drag on the ground. But you can turn them up the other way.


Also need to source QUALITY shackle pins and brackets. Last lot left me a little cold.
Where'd you get them from?

Also need to check the axle location. I found the skid steer centre of balance by driving onto a 2 x 4 and found where it rocked. Should this be where the suspension rocker arm is located?
I'd look at doing that without the bucket, and that would be roughly where I'd put the centre hanger. Then the bucket weight will give you a decent towball load.

Oh, and what about using overide brakes like these instead of electric?
I wouldn't...

[Yonnee]

Thanks Yonnee

Great tips. I will print it off so I can read while away this week.

Any negatives on slipper springs?

Skidder is 1450kg. Leaves 550kg for weight of trailer. Big trailer i built weighs 640kg so should make that weight easy. So all up will be just under 2000kg I imagine. Will definately set it up for dual brakes just in case :2tsup:

Appreciate slipper spring rates :)

Not having any tread plate/ floor. Just a few rails for it to sit on and let the mud fall through. :wink:

Dont think im rude if i dont reply, will be away until sunday night but will jump on when able to.

No worries.
I can't think of any negatives other than they, and the axles, must carry at least 120% of their share of the load. So, 2000kg estimate, tandem axle = 1000kg each + 20% = 1200kg each axle, and 2400kg spring set.

"Slimline" axles are rated at 1450kg each, so you're OK there. Either a 7 leaf x 45mm wide Australian spring set, 8 leaf x 45mm wide Imported set, or 6leaf x 60mm wide spring set will do.

Look at expanded mesh, particularly on the beaver section, for more grip. Remember, you're going to be loading this thing onto the trailer filthy muddy, and therefore slippery. The mesh will at least give you a fighting chance.

[dazzler]

Hey

Well finally got moving. Everything going well. Using CIG Shield Cor 15 gasless flux cored wire with a unimig mini mag Mig welder. This is designed for welding duragal steel but am wire buffing the topcoat of gal off anyway and getting a good finish.

73739

Tomorrow will dry fit up the axles / springs/ wheels to determine the angle for the beaver tail and will then remove the axles etc and put on the LOOOOOOONG drawbar. It will be 1300mm long running back to the front spring hangers.

73737

Ran the skidder on the frame before the spring hangers went on and it sits well. The inner rails support the length of the tracks and is supported at 10 points on the cross rails.

73738

cheers


dazzler

[Yonnee]

Looks good Daz...

I see you went with the Rocker springs...:?

1300mm is not such a long drawbar, even if you did mean 1300mm from the front cross rail. 5' or 1525mm is a standard "long" drawbar.

[dazzler]

Hey

Went with what worked well on the last one so rockers it is. Drawbar is 1350mm from the front of the trailer to the end so about 1400mm to the ball.

Things are going well. :2tsup:

[dazzler]

All done!

Sorry i didnt take many shots of the build. Really busy, but basically the same as the big build.

74317

74318

Its a tight fit between the chassis rails;

74319

74320

Balance point of machine (between the 3rd and 4th idler wheels) sits slightly forward of the middle of the tandem wheels. This gives some towball weight.;

74321

Hey Yonnee, check out the loooong drawbar;

74322

All up weight was 320kg :2tsup:.

Tows great, brakes well. Yet to load without two small 900mm ramps that I have in the truck but the beaver tail is great.

cheers

dazzler

[Yonnee]

Once again Daz, top stuff.

If I may, two suggestions.

1) Butt weld a piece of 50mm flat accross the top of your LED's to give them some protection. The Ledautolamps LED's are pretty tough, but better shutting the gate before the horse bolts.

2) Flip the number plate light and hang your number plate below the cross beam. Stops your No. plate light from getting covered in mud and crap, and then getting a fine because it can't be seen at night.


How's it tow behind the 4by?

How wide is it overall? Obviously less than 1600mm, or else your RTA blokes are slack!!:~

How many goes do you have getting the bucket teeth lined up with the U-bolts?:;

Great job.:2tsup:


Yonnee.

[dazzler]

Once again Daz, top stuff.

If I may, two suggestions.

1) Butt weld a piece of 50mm flat accross the top of your LED's to give them some protection. The Ledautolamps LED's are pretty tough, but better shutting the gate before the horse bolts.

2) Flip the number plate light and hang your number plate below the cross beam. Stops your No. plate light from getting covered in mud and crap, and then getting a fine because it can't be seen at night.


How's it tow behind the 4by?

How wide is it overall? Obviously less than 1600mm, or else your RTA blokes are slack!!:~

How many goes do you have getting the bucket teeth lined up with the U-bolts?:;

Great job.:2tsup:


Yonnee.


Will do both, was trying to work out how to protect the leds. She is 1850mm wide, what did they miss?

Its easy to line them up surprisingly :2tsup:. Just finished the ramps and will test them tomorrow.

cheers

[Yonnee]

Anything over 1600mm wide must have white front clearance lights, and over 2100mm must have red/amber side markers front and rear.

[dazzler]

they blend in with the silver guards :D

74589

Scratched my head when reading the regs however its states;


"Two front position lamps showing white light to the front of the trailer must be fitted to trailers which are more than 1600 mm wide"

They are visible from the front as the jerry holders are about 50mm narrower than the guards. :)

[Yonnee]

Ah... I see now...:doh:

...they don't look like LED's though...:no:


There's a loophole in the reg's that would allow you to put a red/amber lamp on the guard and that would be it. You could mount it on the side of the guard between the wheels (fabricate a neat bracket that would tuck it just inside the outer edge of the guard). Ledautolamps (ledautolamps.com/product-details.php?pid=124) now do one with a reflector in the middle and do away with the one on the jerry can holder.