Pump Drive Pulley

You can see how poor the original drawing was. I have colored the Pump Drive Pulley in red to highlight it in the drawing. It’s large size is to drive the Pump Pulley quite a bit faster than the 250 RPM of the Steam engine.

D=74"
C=232.48"C=19.37'
v_{m}=C_f*RPMv_{m}=19.37*250v_{m}=4,842.5

45 HP : P=\frac{33000*H}{v_m}P=\frac{33000*45}{4843}P=307
20 HP : P=\frac{33000*H}{v_m}P=\frac{33000*20}{4843}P=136

From the ‘Belt Width Table’ we can see that at 45 Hp the belt — b — needs to be 3-1/2″ wide and at 20 HP only 1-1/2″ wide. Pulley width — B — is taken as B=\frac{5}{4}b .. pulley widths are 4\frac{3}{8} and 1\frac{7}{8} respectively.

Running the calculations for where in the text it refers to the Stewart Washery having five jigs with 100 HP .. my ‘assumption’ is that the draftsman shows a single jig for simplicity while showing the engine and pulleys for the full five-jig Washery.

100 HP : P=\frac{33000*H}{v_m}P=\frac{33000*100}{4843}P=681

This requires a 8″ wide belt or a 10″ wide pulley. This is well within the error of me trying to trace a small, blurry image. Since I am modeling a single-jig I am happy to go with the 4\frac{3}{8} wide pulley calculated for 45 HP.

Data

  • \textbf{HP=45}
  • \textbf{Pulley Diameter = D}
    • D = 69"
    • D = 36.52\text{ mm - O scale}
  • \textbf{Pulley Circumference = C}
    • C=18.06'
  • \textbf{250 RPM}
  • \textbf{Pulley Circumferential Velocity} v_{m} (Pulley Circumference in Feet x RPM)
    • v_{m}=C_f*RPM
    • v_{m}=4517 \text{ FPM}
  • \textbf{Pulley Power = P}
    • P = \frac{33000*H}{v_m}
    • P = 329
  • \textbf{Shaft Diameter = d}
    • d = 3"
    • d = 1.59\text{ mm - O scale}
  • \textbf{Belt width = b}
    • b=4"
    • b=2.12"\text{ mm - O scale}
  • \textbf{Face Width = B}
    • B = \frac{5}{4}b
    • B = 5"
    • B=2.65\text{ mm - O scale}
  • \textbf{Rounding of Pulley Face = s}
    • s=\frac{1}{20}*b
    • s=.2"
    • s=.11\text{ mm - O scale}
  • \textbf{Rim Edge Thickness = k}
    • k = 0.08 + \frac{B}{100}
    • k=.13"
    • k=.07 \text{ mm - O scale}
  • \textbf{Pulley Nave Width = w}
    • w = 0.4 + \frac{d}{6} + \frac{R}{50}
    • w = 1.59"
    • w=.85 \text{ mm - O scale}
  • \textbf{Pulley Nave Length = L}
    • L = 2.5w
    • L = 3.975"
    • L=2.11 \text{ mm - O scale}
  • \textbf{Number of Arms = N}
    • N = \frac{1}{2} (5+\frac{R}{b})
    • N = \frac{1}{2} (5+\frac{34.5}{4})
    • N = 6.82
    • N=\text{7 - Rounding up}
  • \textbf{Arm Width at Nave = h}
    • h=0.24+\frac{b}{4}+\frac{R}{10*N}
    • h=1.733"
    • h=0.92 \text{ mm - O scale}
  • \textbf{Arm Width at Rim = }h_1
    • h_1=\frac{2}{3}*h
    • h_1=1.156"
    • h_1=0.62 \text{ mm - O scale}

3D Printing

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