Hydraulics - Seafish

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Figure 1 shows a system using a cylinder to give linear motion. An example of this on a fishing vessel is raising the power block head. Figure 2 shows a system using a motor to give rotary motion and an example of this is using a hydraulic motor to turn the power block drum. Now look at Figures 1 and 2 in turn and follow the system round. Start at the pump and using the arrows, trace the path of the hydraulic oil. Make a note of each item as you come to it. On most fishing vessels there will be at least one of each of the systems shown in Figure 1 and 2. As soon as you have the opportunity and when the weather is suitable, go out on deck and have a look at the power block and its hydraulic system on your vessel. Try to identify the reservoir, the pump, the valves and the actuator(s). Most of these are usually quite easy to identify but the reservoir and the pump may be difficult to find. This is because they are often in the engine room, the pump being driven off the engine shaft. Remember always to ask permission before entering any engine room or before looking around the deck of a fishing vessel of which you are not a member of the crew. Never attempt to move any of the controls you are looking at. Now try your first SAQ. <strong>Seafish</strong> Open Learning
Write down a list of the main components in a hydraulic COMPONENTS OF HYDRAULIC SYSTEMS We will now consider the principal components of a basic hydraulic system in detail. The Tank or Reservoir The tank must be large enough to hold all the oil required to fill the system and some in reserve. As a general guide the tank should be able to hold 2 to 3 times the capacity in minute of all the pumps in the system. litres per The return pipes to the tank are located at the opposite end from the suction pipes because the returning oil is usually hot. Arranging the pipes in this way prevents the hot oil from being immediately pumped through the system again. In some cases the tank may be fitted with an oil cooler through which either sea water or fresh water passes. A baffle plate fitted between the return pipes and the suction pipes helps to take heat away from the oil and release any air which is contained in the return oil. It will also help to separate out any dirt in the oil before it is recirculated. The tank should be fitted with an oil level indicator and in many cases will also have a temperature indicator. <strong>Seafish</strong> Open Learning
Page 1 and 2: SEA FISH INDUSTRY AUTHORITY Hydraul
Page 3 and 4: Hydraulics in Fishing Vessels An Op
Page 5 and 6: SEGMENT FIVE - HYDRAULIC OILS AND F
Page 7 and 8: A Guide for Open Learners This will
Page 9 and 10: VII S.A.Q/S are shown by a box with
Page 11 and 12: IX • Time spent just reading a mo
Page 13: XIII Objectives After completing th
Page 17: Working cylinder V 7 3 •< ► Loa
Page 21 and 22: In this type the rotor shaft is off
Page 23 and 24: 8 Pressure Control Valves Positive
Page 25 and 26: 10 Relief valves are either pre-set
Page 27 and 28: 12 (A) From Pump (P) i a(B) Raise H
Page 29 and 30: 14 Out Out Globe valve Figure 17. S
Page 31 and 32: 16 (?) SAQ25 Explain how a relief v
Page 33 and 34: 18 The cylinders shown in Figures 2
Page 35 and 36: 20 Figure. 31. Figure 32. Port A Po
Page 37: 22 Which types of pumps can be used
Page 41 and 42: 24 Hydraulic Pressure The pressure
Page 43 and 44: 26 In order to help you to compare
Page 45 and 46: 28 ® SAQ18 Using Figure 35 on page
Page 47: 30 ® SAQ29 When a hydraulic motor
Page 51 and 52: 32 Rotor Inlet External Gear Pump F
Page 53 and 54: 34 The vanes are pushed out by cent
Page 55 and 56: 36 Piston Pumps All piston pumps de
Page 57 and 58: 38 Drive shaft flange Piston Yoke c
Page 59 and 60: 40 Eccentric Oil outlet Figure 49.
Page 63 and 64: 43 Segment Four — Hydraulic Syste
Page 65 and 66: 45 K4SS^^ LINES AND LINE FUNCTIONS
Page 67 and 68: 47 PUMP ONE-WAY VARIABLE OUTPUT PUM
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49 • Pilot pressure means that oi
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51 ® A reversible motor with a bra
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53 (?) SAQ15 Using the information
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55 First, identify each of the item
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57 ® SAQ28 Using the diagram of Fi
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59 SUMMARY You have now completed S
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62 PROPERTIES OF HYDRAULIC OILS The
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64 (2) SAQ20 How is the viscosity o
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66 (?) SAQ26 Using Table 3 determin
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68 Additives in Hydraulic Oils Many
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70 CONTAMINATION Dirt and other for
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72 • Metal wear particles • Pac
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74 Full flow filters are all fitted
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77 Segment Six — Maintenance and
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79 Cleanliness has top priority.
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81 Do not 'grip' a hot pipe. Try a
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83 Faulty Seals Faulty Seals on pum
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85 Excessive Noise Table 4 Seafish
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87 Incorrect Flow Table 6 Seafish O
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89 Faulty Operation Table 8 Seafish
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93 So you can see that there are ma
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95 Responses to the Self Assessment
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97 SAQ 6 Did you show the change in
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99 SAQ9 The various properties whic
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101 SAQ15 SAQ16 A linear actuator p
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103 SAQ20 (a) Viscosity increases a
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105 SAQ26 SAE 20W/30 oil will have
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Other modules in this series which
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Hydraulics - Seafish

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