### 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"$$C=19.37'$
$v_{m}=C_f*RPM$$v_{m}=19.37*250$$v_{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

0 0 votes
Article Rating
Subscribe
Notify of
0 Comments
Inline Feedbacks
View all comments