Weights of loads

[Mark Chisholm]

I recently went to the Penn-Del ISA annual symposium and soon found out how important (many feel)it is to try to understand how to calculate the weight of a tree section. This was a hot topic when paired with the use of a crane. I was surprised to hear how many climbers have worked on cranes for years and years yet never on a crane with a weight scale. I believe that this could be one of THE best training tools available to us in the field! I highly recommend taking any opportunity that comes your way to employ a large crane. It is an eye opening experience.

What I have found is that cranes rated for 28 tons or more will usually have a scale. With this you gain the ability not only to know what each section weighs, but you also can get an idea how a rotation after a cut can add force to the system. The operator (or other person) can watch the scale and see when the force rises and falls. This is extremely valuable. Just make sure that you add in the weight of the ballist!

 

[joe]

Hi, Mark;

I have to appreciate this sort of tip. However, a man with a large amount of resources availabe to him, like yourself, will have the ability to use such a large piece of equipment as a learning tool. I'm not 1 of the people
with this sort of resource available to him.

I do think it is practical to have fundamental scientific principles available as a resource to understand rigging weights, designs, and motion. The science would help show why a piece of equipment is limited to any size section wood if it is a limitation of the specific piece of equipment being used.

I also believe it's important to know and understand wood weights and motion. Having been trained without this knowledge, then acquiring better information later proved to me I should know it.

Considering I don't know what your talking about when you say the ballast needs to be accounted for when reading the weight on the crane scale, would you enlighten me and tell me about the ballast?

Joe

 

[Mark Chisholm]

Hey Joe, knowlege is key! I like what you're saying about learning and applying principals.

I like to do the same (whenever possible).

As for the large crane idea, well if you need to rent a crane for a particular job (which we personally do on a semi-regular bassis), try to get one with a scale whenever possible. The difference in daily rentals may only amount to an extra couple of hundred dollars on the day. That extra money can be a huge allowance for a grand training experience. It was definitely so in my case!

If you price a job to allow for the use of a crane, check with the rental office first and then adjust your estimate as needed. We usually pay between $850.00/day to $1800.00/day for our cranes. A 28-36 ton will be in the $850.00 range and an 80 ton will go for $1800.00 (all with operator). Most cranes over 25 Tons will have a scale.

Sorry about not explaining the "ballast" concept more. All that I was saying was that many climbers have neglected to add in the weight of the hook and pill (ballast). On large cranes it can take up as much as 750# of your overall capacity. This can be critical if you are crunching #'s and the boom is near capacity.