Design a simple hydraulic circuit which will operate a hydraulic cylinder of the
machine. The load during the forward stroke is 20KN and that during the return
stroke is approx. 10 KN. The forward and return speed are about 3 m/min and 5
m/min, respectively. Total stroke of the cylinder is 300 mm. Provision is required
to hold the cylinder anywhere in between the end positions. Select different
components from the data given in Table 1. Specify ratings, of the components in
case it is not available. (P6)
𝐅𝐞𝐱𝐭=𝟐𝟎𝐊𝐍=𝟐𝟎𝟎𝟎𝟎 𝐍
So first select pump from given design data having maximum pressure 𝐅𝐫𝐞𝐭=𝟐𝟎𝐊𝐍=𝟐𝟎𝟎𝟎𝟎 𝐍
Design calculation for forward stroke, 𝐕𝐞𝐱𝐭=𝟑 𝐦/𝒎𝒊𝒏=𝟎.𝟎𝟓 𝐦/𝒔
In data maximum pressure is 70 bar 𝐕𝐞𝐱𝐭=𝟓 𝐦/𝒎𝒊𝒏=𝟎.𝟎𝟖 𝐦/𝒔
By substituting above pressure, find the diameter of piston
20000
Then P = (𝐹𝑒𝑥𝑡 /𝐴𝑝𝑖𝑠𝑡𝑜𝑛 ) → 70×105 = 𝜋
×(𝐷𝑝)2
4
20000
So 𝐷𝑝 = √𝜋 = 0.060314 m =60.31 mm
×70×105
4
From design data select actuator having diameter equal or more than 60.31
Select A4 Model, 𝐷𝑝 =75 mm, 𝐷𝑟 = 45 mm
By considering the above actuator Calculate the pressure build in circuit for forward and reverse
stroke.
20000
𝐹𝑒𝑥𝑡 = (𝐹𝑒𝑥𝑡 /𝐴𝑝𝑖𝑠𝑡𝑜𝑛 ) = 𝜋 = 45.27 bar
×(0.075)2
4
𝜋
𝑄𝑒𝑥𝑡 = 𝐴𝑝 × 𝑉𝑒𝑥𝑡 = × (0.075)2 × 0.05 = 2.2 × 10−4 𝑚3
4
/s =13.25 LPM
10000
𝑃𝑟𝑒𝑡 = (𝐹𝑟𝑒𝑡 / 𝐴𝑝𝑖𝑠𝑡𝑜𝑛 _ 𝐴𝑟𝑜𝑑 ) = 𝜋 𝜋 =
×(0.075)2 − ×(0.045)2
4 4
35.37 bar
𝜋
𝑄𝑒𝑥𝑡 = (𝐴𝑝 -𝐴𝑟 ) × 𝑉𝑟𝑒𝑡 = { 4 × (0.075)2 −
𝜋
4
× (0.045)2 } × 0.08 = 2.34 × 10−4 𝑚3 /s =14.08 LPM
By calculations we get maximum pressure and maximum flow rate required for the system
𝑃𝑒𝑥𝑡 = 𝑃𝑚𝑎𝑥 = 45.27 bar, 𝑄𝑟𝑒𝑡 = 𝑄𝑚𝑎𝑥 =14.08 LPM
Now select required components from data design but designer must have an idea about
components required to build a hydraulic system
So we first draw the hydraulic circuit
Select components from design data
𝑃𝑚𝑎𝑥 = 45.27 bar, 𝑄𝑚𝑎𝑥 = 14.08 LPM
1- Actuator: A4 already selected 𝐷𝑝 =75 mm, 𝐷𝑟 = 45 mm
2- Pump-model - P3
3- Reservoir:
Capacity =Q max ×3 =14.08×3= 42 liters
So model selected is T2
4- Suction strainer (Filter), the model that should be
selected is S2
5- Pressure relief valve (PRV), the model that should be selected is R3
6- Pressure gauge (PG), the model that should be selected is PG3
7- Direction control valve (DCV), the model that should be selected is D2
8- Flow control valve (FCV), the model that should be selected is F4
9- Check valve (CV), the model that should be selected is C2
