Improving?? Athearn's Mack Model B Wrecker

[up1950s]

Thats a great improvement . I will need to do that myself when I get around to vehicles again .

[3rdrail]

It looks even more amazing in person, those cables are .003" and are barely visible to the naked eye! Great job, Bill. 

[Bangorboy]

Thanks, guys!

I knew I was pleased with the outcome for my first attempt to upgrade a vehicle.  I wasn't so sure anyone else would be impressed with it. 

I appreciate the encouragement.

Bill

[JDouglasFisher]

Being a retired wrecker operator, I've always been annoyed when people model wreckers and rollbacks without really going into details, or perhaps posing them at model scenes of wrecks, in positions that wouldn't work.

Bill, you actually got it right, the rigging in "transit" mode is spot on, and considering this is N scale, a feat in and of itself.

Probably the only complaint I have, (and definitely not worth the effort in N scale) is that the winch cables (proper term is wired ropes) should be painted a dark greasy rust brownish black color.

For those who are interested a bit more, the model most closely represents a Holmes model 750 body, obviously mounted on a B model Mack chassis. Only thing its missing is the stablizer legs used during recoveries in which the booms are swung outboard of the body to perform winching, such as recovery from a deep ditch, or a rolled over truck.

Add a couple scale 4'x4"x4" (yes, four foot long, 4 inch square timbers) boards lying on the back deck, and your set. (the boards are used when hooking up the truck bar to the towed vehicle, keeps from scratching the bumper of the towed vehicle, as well as spacing the tow chains away from it...)

The boards should be dirty, greasy as well.

Good job Bill, I like it, and I am impressed that Athearn actually got it pretty close to right. Previous wrecker and rollback models from other manufacturers have been disappointing to say the least.

Joe.

[Bangorboy]

Thank you!  Thank you!  Thank you!

I consider this quite a compliment.  I was shooting for a model that gives the impression of the real thing, in order to look realistic.  Coming from someone who spent years working with the prototype, your comments carry a lot of weight with me.  I couldn't ask for more validation of my effort.

I had searched the web for pictures of Holmes wreckers.  The only two pictures I could find with clear enough depiction of the rigging to use were a shot of a mid-1980s Chevy light duty Holmes and a Holmes brochure.  The Chevy looked like probably a 1-ton chassis and the wrecker structure was obviously lighter duty than my model, but I assumed the rigging would be similar even if of lighter structural materials.  The brochure was a .pdf file of a much heavier wrecker, but it was blurry in the enlargement.  I don't think it was scanned at a high enough resolution.  It did show the directions the wire ropes were strung and compared with the Chevy picture led me to the rigging I ended up with.

Thanks again.  I'm even more happy with my model now!

Bill

[JDouglasFisher]

Heres some websites for you to enjoy...

www.recoveryvehicles.com/history.htm
European Site, but Holmes bodies were universally sold in both North America as well as world wide.

http://rides.webshots.com/album/116208177WBeZZP?vhost=rides
Webshots album dedicated to "antique" wreckers,

http://public.fotki.com/modeltrucks25thscale/truck_brochures/holmes_wreckers/various_holmes_wreckers/
Some old brochures that the Ernst Holmes Company used to promote their product.

http://www.internationaltowingmuseum.org/
International Towing and Recovery Museum and Hall of Fame

Despite the Holmes company being absorbed into the Miller family of wrecker builders, these older mechanical and semi mechanical wreckers are still sought after by many in the industry who actually know how to use them to their fullest extent. Todays Hydraulics are convenient but a Holmes 750 in the hands of a very good operator can do just about anything, including pulling buildings down.

For those who model modern day, try kitmingling this body onto the back of a Atlas N Scale Ford Tractor.

Joe.

P.S. I'm retired early from the towing industry, at 32 years old, (with 11 years behind the wheel) and having been hit by cars twice, with little to show for my service, it was time I switched gears literally, and sought a new career. Despite my exit from the industry, I still keep tabs on whats going on, too many friends, and its in the blood.

[Bangorboy]

Do you mind a couple of questions, Joe?

How much tow rope was available on the Holmes 750?

(I'm assuming the boom lift ropes were long enough to cover four passes between the mast and the boom with the boom lowered to horizontal or maybe even depressed a little for downhill reaches.)

How are snatch blocks used?  Are they chained to trees or other available anchors and the cable strung through them?  Also, in transit are they carried stowed in compartments or loose on the bed of the wrecker?

Would a typical wrecker have some lengths of chain coiled or piled on the deck?

Enjoyed the web sites.  Will probably revisit them to see what I missed the first time around.

Thanks again.

Bill B

[Wlal13again]

Bill,

Have you ever watched the show Wrecked on the SPEED channel? It`s a reality show about large towing company in Chicago. Some really good recovery episodes.

I took this picture last year, sorry I didnt get a rear shot. I am going to a Mack Truck show this weekend, if this truck is there, I`ll grab some shots if you want them..



rich

[JDouglasFisher]

Do you mind a couple of questions, Joe?

Nope, I'll answer them as easy as I can.

How much tow rope was available on the Holmes 750?

Silly as it sounds, it was a customer chosen option. With medium and heavy duty wreckers, such as your model, anything less than 100 feet is useless. Most operators I know, to this day, even on modern equipment, run between 150 and 250 feet on the winch drum. Anything more than that, what happens is that your winching capacity decreases as more cable is wrapped in layers over the drum. A good operator will try to match the length of his cable, to the width of the winch drum so that when its fully winched in for transit purposes, it should only layer over itself 3 times on a heavy duty truck.

The reason why these practices are still used is not because the equipment has changed, its because the physics behind leverage and pull haven't changed.

(I'm assuming the boom lift ropes were long enough to cover four passes between the mast and the boom with the boom lowered to horizontal or maybe even depressed a little for downhill reaches.)

It could be done that way, but is overkill. With the booms lowered full horizontal, there should still be 4 winds of cable on the winch drum (minimum required to guarantee that the cable won't rip itself loose from the winch drum itself, which is held in place with a countersunk screw to the drum.) Winched up to almost full vertical, I it should be close to a full drum, 1 layer across.

As an aside, rarely, if ever, would you lower your booms full horizontal, as that would negate the idea of leverage. In most cases during a recovery, you try to keep a 30-45 degree angle on the winch cable over the top of the sheave wheel at the end of the boom, to utilize maximum leverage, thus making the equipment work less hard.

How are snatch blocks used?  Are they chained to trees or other available anchors and the cable strung through them?  Also, in transit are they carried stowed in compartments or loose on the bed of the wrecker?

Snatch Blocks are a means of multiplying leverage. For instance, on a regular, ordinary, modern flatbed truck, the winch capacity is roughly 10,000 pounds, straight off the drum. Lets say I have a plumbers van with no wheels (because it was jacked, and the wheels were stolen, hahaa). Plumbers vans are notoriously known for being excessively overweight (copper pipe, etc.). So knowing that the van has to weight atleast 10,000 lbs if not more, with no wheels, I know that If I run straight off the winch drum, I'll probably snap my wire rope, and possibly behead myself (it has happened..)

By rigging a chain and snatchblock to the Van, and running my wire rope off the drum, through the snatch block, and back towards a tie down point near the winch, I have done 2 things: First, I doubled the time it takes to winch the vehicle onto the truck, but the trade off is I doubled the winch capacity, in effect, I turned a 10,000 lbs winch into a 20,000 lbs winch. I'll trade the speed for ability anyday.

Snatch blocks are just single sheave wheel pulleys, and work very much the same way as with cranes.

Back in the old days, you would anchor your truck to anything, trees, guardrails, bridge rails, another truck.

Nowadays, although there are some people who won't get schooled, we are taught that you don't tie off to anything if it doesn't have a load bearing plate on it, I.E. a tree for instance. With proper training, you could work just about anywhere with 1 or 2 trucks, and do almost anything. I even used a police car once as a counter weight during a rollover on the highway.

Realize too that the towing and recovery industry has come a long way from its beginnings. Up till about the 80's, there wasn't a real science behind it, and many operators just operated from the hip, not knowing how to fully use their equipment. These days, we have courses that one can take to learn all the ins and outs, and optimize use of the equipment. Thats why I laugh at companies who insist on buying that new $500,000, 70 ton capacity, sliding rotator heavy duty wrecker, and then they stick a guy in it who has no clue what the hell they are doing.

Its even more funny when the local old timer comes out with his 1970's era Autocars, with Holmes bodies on them, and uprights tractor trailers in an hour...

I've been trained through Wreckmaster, though there are other options such as the Towing and Recovery Association of America (TRAA) and I believe the University of Georgia has an excellent program.

See below for storage of snatchblocks.

Would a typical wrecker have some lengths of chain coiled or piled on the deck?

Again, operator preference. Back in the old days, everything was legal. Storing snatchblocks and chains properly in the tool boxes made it easier to find them when time came to actually use them, but not everyone is tidy with their truck. Usually, the owner/operator is either very organized, or very unorganized. Not that an operator couldn't coil chains on the back deck, but usually they were stowed away, or just thrown haphazardly on the back deck.

These days, you can't "legally" do that as its a Federal Motor Carrier violation, (not to mention most state DOT's as well) but as with everything else, its subject to enforcement. Most people do use their tool boxes now because they don't want to get the fines, plus with many law enforcement agencies requiring "Quick Clear" methods these days on the roadways, organization greatly reduces the time it takes to upright a vehicle, and clear it off the roadway to the shoulder.



Any other questions?

Joe.


 

[Bangorboy]

Can think of only one more question, Joe.  What is the diameter of the pulleys/sheaves on the mast and boom rigging?

You gave me more information than I asked for, and answered a lot of questions I would likely never have thought of.  The idea of too much rope on the drum, for instance.  It does make sense that it increases the diameter of the drum, and that would add stress to the mechanism that drives the drum by giving the load a greater moment to fight the pull.

Rich,  Thanks for the pic you added.  It's cool.  If you do get a chance to get some pics of the Holmes body, I'd enjoy seeing them.

This turned out to be a very informative exchange, thanks to you guys.

Bill

[JDouglasFisher]

You know Bill,

I never actually measured one, but from having been around them I would say somewhere around 8 or 9 inches diameter would be good.

Joe.

[Bangorboy]

Good.  An estimate is good enough, and 8 or 9 inches is a lot easier to make in N Scale than 4 or 5 inches.  The only way I know of to make them is to punch two discs of one size and a third disc slightly smaller, and TRY to keep them centered as I glue them together.  The smaller they are the harder this would be.

I'm not even sure I will try to replace the blobs on the Athearn model with scratch built pulleys, but I might....

Thanks again.

Bill

[Wlal13again]

Sent you a PM Bill...