Steering is positioned - only thing missing now is one more axle!

Good work, Mike!

Right now an "all steer" 6x6 but soon to be an 8x8!



Step Two - ROUNDS COMPLETE!

I am fairly stuck, not being able to move forward on this project till the second kit comes in which is not scheduled to arrive until Dec. 6 at the earliest!

I guess I will be working on general details and the cab interior till then.

Excellent quality set of etch comes with the Trumpeter Mk 23. However they could have also included interior door grab handles, window cranks and rifle racks.

Will be looking forward to your next update!

British Oshkosh semi-tractor (based on Mk23) over on Prime Portal at:

http://data.primeportal.net/hoare/OSHKOSH%20FUEL%20TANKER%20(TRACTOR%20UNIT).htm

Nice, I like the look of the extended cab.

I like that semi. It seems that Oshkosh has a size for every need. (Other than the Volkswagen set at least.)

As I say I am going to try to clean up some other details while waiting for that second Mk23 kit to show up.



Tonight it was the cab dashboard and seats. I scratch/converted the gunner's seat back to give him something to stand on. I also filled in the back of the driver's seat just for grins. Do not know why Trumpeter would not have given us a passenger seat that would fold down. The seat back brackets the real thing slide up and down vertically on the two side posts when the seat is folded down. They could have given us two sets of brackets, one set for up and one set for down. They got so close but no cigar.

I think I might put a few 50 cal. cans in that storage space behind the passenger seat just to give the guy more area to stand on.

Next up is to frame up the inside of the cab just a bit to give more of a 3D quality to those otherwise blank inside walls.

Nice work on the cab. I especially like what you did with the passenger seat. I wonder where that idea came from?

It came from a fellow named Gino, I believe!

p.s. I have now found photo reference for Mk23 dashboards that are painted totally black and others painted the same green as the cab interior so take your choice in that department.

Asking here if anyone has further info or plans on this pivoting structure that seems to be at the rear of almost all / or all PLS trucks and any LHS trucks that use the X-frame device for non-flatrack container handling. I think I am going to have to be building these for my 16.5 ton Mk23 LHS.

Hi, Mike!

Do you remember back a few months ago when we discussed Chassis Geometry and Wheel Alignment? Specifically, Caster, Camber, Toe-In and Toe-Out On Turns..? I REALLY don't mean to be a pain, and I'm not downing your work, (which is exemplary, BTW), but looking from overhead, if the angles on your axles (#s 11 & 12 in your photo), were on a real vehicle, they WOULD BE FIGHTING EACH OTHER IN ORDER TO MAKE A TURN. (and driving you crazy in order for you to maintain control of your vehicle) The OUTSIDE Wheel/Tire should have a LESSER ANGLE than the INNER Wheel/Tire. This is because the OUTER Wheel/Tire needs to run in a WIDER DIAMETER of the TURNING CIRCLE, while the Inner Wheel/Tire needs to run in a TIGHTER CIRCLE. If it weren't for Toe-Out On Turns, you'd be constantly fighting your Steering Wheel, even in the slightest turn.

Conversely, if you were displaying your vehicle with 0-degrees of "turn", then you'd need to show a slight amount of "Toe-In". The Toe-In serves the same purpose, in principle, as the Toe-Out On Turns. When a wheeled vehicle is traveling in a straight line, the faster it goes, the more the (steering) Wheels/Tires want to splay OUTWARDS at the FRONT, as you're looking from above or below. The Toe-In compensates to counteract this tendency. THAT is just basic physics. (see above, Re: being driven crazy and fighting your Steering Wheel) You'd NEVER want to drive your car or truck ever again, if it weren't for properly adjusted Wheel Alignment and Chassis Geometry...

Also, check your Camber- Looking Head-On, or from the Rear of the vehicle, the TOPS of the Left & Right Wheels/Tires should have a GREATER distance between them than the BOTTOMS. This difference in distances should also be evident if your vehicle is displayed with 0-degrees of "turn"...

Please don't misconstrue my pointing out these tenets of Chassis Geometry and Wheel Alignment as negative criticism- On the contrary, I only mean to help...

Caster, on the other hand, is not obvious when viewed from the front, rear or sides of the Wheels/Tires, as this adjustment is hidden from view. Caster enables your Wheels/Tires AND your Steering Wheel to RETURN to a "neutral", or "straight-ahead" position, without YOU having to do so, after coming out of even the slightest turn...

Hope this helps...

GREAT WORK, on this latest build of yours!!!

It looks like the Trumpeter M1120 LHS will have the new setup for the container handling equipment, including the pivoting guide you show above. Hopefully it will be available soon.

Also found a walk-around of an M1120 LHS w/CHU (Container Handling Unit) on Prime Portal. There are some good views of the pivoting guides.

Check it out here.

Thanks Gino I somehow managed to miss those CHU photos on Prime Portal. Pascal strikes again!

As to the Trumpeter HEMTT with LHS & CHU, I have my fingers crossed but do not have much hope that kit will make it time to support my current Mk?? project.

Dennis I may not have gotten the steering exactly correct but believe me I had your influence in mind when I was trying to set up the steering angles. The outer wheels scribe a wider circle than the inside wheels which are set to a tighter turning radius.

Right now I think the front axle angles look too sharp but bear in mind that the lengthening of the frame and the #2 non-steering axle have yet to be applied to this truck. Hopefully everything will work out once the frame is in its' final form.

I also wanted to share this photo I recently found in an Oshkosh publication showing what appears to be a special 6x6 semi-tractor set up with both the front and rearmost axles steering.

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Dennis is it possible that you are looking at the rear axles as having what you would consider an excessive amount of toe-in?

I believe that in rear wheel steering the "toe value" is roughly a reverse mirror image compared to that of the front steering axle. The rear steering axles toe-in should be looked at, and measured, as though the vehicle were rolling in reverse.

I know my wheel steering angles are not EXACTLY right but I think they are in the ball park, however I realize I could be totally wrong.

As to the wheel camber, I let the structure of the model itself dictate what camber that it would, which I admit is very little. However the double A-arms of the Oshkosh suspension are of equal length and it appears the Oshkosh design itself does not allow for much in the way of camber in the steering geometry. If I am correct in this camber question I do not know. Also what this may imply for this particular vehicle design I again, do not know.

Hi, Mike, and Everyone else!

OK, let me try a different tack, here. Whether it's the Front Wheels/Tires or the Rear set, the same rules of Caster, Camber, Toe-In, and Toe-Out On Turns still apply:

Camber: Looking "Head-On" from the Front, (standing at the Front of the vehicle, and looking at the Nose) AND the Rear, (standing at the Rear of the vehicle, and looking at the Rear End), the Wheels/Tires should be splayed OUTWARDS, i.e, Right and Left, at the TOPS of the Wheels/Tires- This shouldn't be exaggerated by any means, but this characteristic should be, at the very least, noticeable if one looks closely.

What I do to present Camber, is that I like to GENTLY apply slow, steady pressure downwards to the Axle Spindles, altering the Axles to point slightly down, when viewed from "head-on", or from the rear. Too much pressure will break the Axle Spindles, so a light hand is essential in doing this. For "newbies", I suggest practicing on pieces of sprue before attempting this technique.

Toe-In: If the Wheels/Tires are modeled as traveling "straight-ahead"- Looking from Above and/or Below the vehicle, ALL Wheel/Tire assemblies, regardless of their positions on the Chassis, i.e, Front, Middle or Rear, should show a VERY slight Toe-In, or what I sometimes call "pigeon-toed-ness".

On real vehicles, this is essential in order to prevent the Wheels/Tires from splaying Outwards at the Front when the vehicle is traveling Forwards. This outward splaying becomes progressively worse as road speeds are increased. We travel forwards probably 99% of the time, rather than backwards as a general rule. As I mentioned in my previous post, this is to prevent the splaying of the Wheels/Tires. This splaying in turn, will cause the the vehicle to wander VERY excessively, and cause excessive Tire & Tie Rod End Wear, because the Right and Left Wheels/Tires want to travel in opposite directions as you're driving forwards. Tires and Tie Rod Ends are expensive, plus constantly having to fight your steering directions and maintaining a straight line down the road can be pretty darned frustrating into the bargain...

The Upper and Lower "A" Arms don't necessarily need to be of equal lengths; the designs of the "A" Arms vary between vehicle manufacturers- The adjustments for Camber are made at either the Top "A" Arm, or at the Bottom "A" Arm, most commonly in the Upper and/or Lower Ball Joints, depending on the design that any particular manufacturer chooses to use in their products. The actual Length of the Upper and Lower "A" Arms have NOTHING to do with ANY Wheel Alignment adjustments.

I'm SURE that you understand the Toe-Out On Turns, judging from your latest line-drawing in your last post.

Now, on plastic models with "pose-able" steering, the model manufacturers all too often leave you with way too much "slop" in the Steering assemblies' parts, just to facilitate ease of "posing" your Wheels/Tires in any direction you happen to choose. This "slop" will COMPLETELY throw the model's "Wheel Alignment" out of kilter. The WEIGHT of the model will determine how much the Wheels/Tires will splay OUTWARDS AT THEIR BOTTOMS, rather than at the TOP, when the model is placed on a flat and level surface. The model's "Wheel Alignment" will thus be rendered as COMPLETELY INCORRECT, presenting a decidedly "KNOCK-KNEED" appearance when viewed from virtually ANY angle. The ONLY way that proper Wheel Alignment really works on wheeled vehicle models, is to CEMENT the parts of your whole steering assembly in place, once you've decided on which direction you want to pose your Wheels/Tires. IMO, if you leave all the "slop" in your Wheels/Tires and their respective Steering Mechanisms, you're gonna wind up with a model that has cock-eyed looking Wheels...

Call me obsessive, but over 25 years of experience in the Automotive and Heavy Machinery businesses have made me a STICKLER for accuracy. Once AGAIN, let me STRESS that I AM NOT CRITICIZING your work, merely making SUGGESTIONS...

BTW, speaking to the modellers who "cross-cultures", these basic Wheel Alignment tenets also apply to scale Aircraft Landing Gear Wheels and Tires, EXCEPT for Toe-Out On Turns. Aircraft are steered without any automotive-style steering mechanisms-

Aircraft steer by several different methods, i.e, with "Tail-Draggers", (Aircraft with tail Wheels, as opposed to Aircraft with Nose Wheels), by the Pilot(s) applying brake pressure at the tops of either the Right or Left Rudder Pedals where the Brake Actuating Mechanisms are located, OR by unlocking the Tail Wheel, AND using the Rudder Pedals, applying Brake Pressure at the same time. Interestingly, this method of steering is kind of similar to steering tracked vehicles, along with Steering Levers which activate the Steering Clutches, which are located internally, outboard of the Transmission...

In the predominating cases of Aircraft with Nose Wheels, the Pilot(s) will use the Control Wheel (as with wheeled ground vehicles), along with Brake Pressure, applied by using the tops of the Rudder Pedals.

Slight Camber and Toe-In are DEFINITELY required on Aircraft, what with their high Take-off & Landing speeds, and their much heavier weights notwithstanding...

Dennis, perhaps you should stop stating general rules and just tell me what I am doing wrong relative to this particular model. I don't seem to be able to translate your general rules into corrections to what I am building here.

Before our last discussion over my HEMTT LHS I thought that toe-in should ALWAYS be present regardless of steering angle. Then you talked of how the inside wheel in a turn has to inscribe (follow) a tighter turning circle. I don't see how the inside wheel can follow a tighter turning circle and still maintain toe-in relative to the outside wheel.

I guess I have to say our various conversations have me more confused than ever. And this is about something I thought I had at least a general grasp of.

Please know that the steering on this Mk?? LHS is glued down so there may be little I can do now to correct this model. However I still have one more wheel on the HEMTT to correct and perhaps our further discussion here could help me to keep from making that model more incorrect.

Confused in Lexington!

Maybe this will help??

http://www.hunter.com/Portals/0/Media/995-T-2.pdf

http://www.repository.up.ac.za/bitstream/handle/2263/29026/dissertation.pdf