Section IV : Belt Elevators

Two Elevators and one conveyor

The drawing was made c.1906 while the reference book I have was published in 1922. I assume that there may have been a change in describing conveyors and elevators during that time as what are labeled Conveyors on the drawing are obviously termed Elevators in the reference book..

There are two Belt Elevators shown in the drawing – with a third Belt Conveyor apparently feeding the Washed Coal Bin. That one I will leave alone for now (I did notice that it is a flat Belt Conveyor unlike the two Belt Elevators. For now I will pay attention to them.and pay attention to those two.

In 1979’s Extraterrestrial Civilizations, Isaac Asimov estimates the probability of there being intelligent extraterrestrial civilizations within the Milky Way galaxy. This estimation is approached by progressively analyzing the requirements for life to exist. In this book Isaac often referred back to the “Theory of mediocrity” — The mediocrity principle is the philosophical notion that “if an item is drawn at random from one of several sets or categories, it’s likelier to come from the most numerous category than from any one of the less numerous categories“.

I will use that principle as interpreted by Isaac that with a single source to choose from .. such as the drawings of these Belt Elevators — that that IS the most numerous example .. being the only one .. so unless convinced otherwise will go with these as being correct.

Some early thoughts:
The buckets are smaller and closer together and the belt narrower on the Crusher Belt Elevator. and wider on the Washed Coal Belt Elevator and spaced further apart and wider.

The dimensions are shown below – the idea is to use those numbers to try and get a better design using Belt Conveyors and Belt Elevators by Frederic V. Hetzel, M.E. pub 1922

Dimensions

• Crusher Belt Elevator:
  • Center/Center axles: 45′
  • Belt Width: 24″
  • Step Width: 15″
  • Step Height: 10″
  • Step Spacing: 13″
  • Head Pulley Dia: 40″
  • Head Pulley RPM:64.52 RPM (based on engine at 250 RPM)
  • Belt Speed FPM: 675.61 v_m
• Washed Coal Belt Elevator:
  • Center/Center axles: 37′
  • Belt Width: 36″
  • Step Width: 15″
  • Step Height: 10-1/2″
  • Step Spacing: 30″
  • Head Pulley Dia:
  • Head Pulley RPM:
  • Belt Speed FPM:

Overview – of a sorts

Belt Conveyors and Belt Elevators goes into excruciating detail. I don’t need all of that .. just enough information to create a reasonable replica in scale. So for now .. I will just pull excerpts from the book .. simply gathering information for the now .. much like collecting mushrooms in the forest and only later tossing out the ones that will poison you.

• (page 207) Kinds of Belt Elevators — Any kind of belt with buckets attached can be run around an upper pulley and a lower pulley, and it will elevate loose material.
• (page 207-208) Centrifugal Discharge Elevator — If the belt speed is high enough the contents of  the buckets will be thrown out in passing over the upper pulley (head pulley) and will fall into a chute set to clear the descending buckets.. ^[1]correct nomenclature ‘discovered’. The upper pulley is called the head pulley. This is a Centrifugal Discharge Elevator (Fig. 200); it may be vertical or it may stand at an angle.
• (page 208) Nearly all centrifugal discharge elevators have spaced buckets with rounded bottoms; they pick up their load from a boot, a pit or a pile of material at the foot pulley. ^[2]correct nomenclature discovered. The lower pulley is called the foot pulley
• (page 208) Continuous Bucket Elevators — If the buckets are triangular in cross-section and are set close on the belt with little or no clearance between them, the machine is a Continuous Bucket Elevator (Fig. 201) (…) The chief use of continuous bucket elevators is to carry difficult materials at slow speed

At this point I stopped to consider the drawings of the two Belt Elevators. Some make take exception to the buckets are drawn and our take from said drawings. Yes the draftsman may have simply simplified or misunderstood what he was attempting to portray but .. we have to use the ‘Theory of Mediocrity’ — I will use the acronym TOM from this point on .. and simply go with what we have.

• Crusher Belt Elevator: The buckets appear to be triangular in profile. They are 11″ wide, 10″ high and are spaced 13″ center/center which gives a 2″ gap between them
• Washed Coal Belt Elevator: The buckets appear triangular but with one side longer. They are 15″ wide, 10-1/2″ high and are spaced 30″ center/center which gives a 15″ gap between them

Early classification of the two Elevators: If we base what kind of Belt Elevator we have on the spacing of the buckets then I would at this point classify the Crusher Belt Elevator a Continuous Bucket Elevator based the 2″ gap between buckets. I would classify the Washed Coal Belt Elevator as a Centrifugal Discharge Elevator based on the 15″ gap between buckets.

Elevator Buckets:

• (page 208) Buckets with rounded bottoms (are…) generally used in centrifugal discharge elevators
• (page 208)Buckets with angular bottoms (…) more often employed in continuous bucket elevators for coars, heavy materials
• (page 209) Cast malleable-iron buckets, for coal, ores, minerals and other coarse, heavy materials.
• (page 209) Two-piece or three-piece buckets of heavy steel plate made with angular bottoms for continuous bucket elevators

(page 210) Discharge at the Head. — In some forms of chain elevators the buckets discharge on the lift, but all belt elevators the buckets discharge at the head into a chute set to catch the material, either as it is thrown out by a centrifugal discharge elevator (Fig. 200) or as poured out by a continuous bucket elevator (Fig. 201).

Note: On page 212 there is a discussion of head wheel diameter, RPM and belt speed for centrifugal discharge and a Table 35. This may not be necessary information but I put this as a marker in case I need to refer back to it. (in the discussion, a centrifugal discharge elevator is one that runs at a speed high enough to discharge the contents of the buckets clear of a vertical run of descending buckets. At this point I am going to jump around to estimate the head wheel (pulley) diameter, RPM and belt speeds for the two elevators.