ix Copyright Goodheart-Willcox Co., Inc. Heavy Equipment Power Trains and Systems 26 • Technicians must be equipped and trained for proper use of personal protective equipment (PPE). • Technicians must receive instruction on safe work practices. • Safety data sheets (SDS) must be on hand for all chemicals and hazardous materials being used in the shop. • Heavy equipment technicians often work alone in remote locations and need to be prepared for emergencies. • All shop personnel should be aware of the location of the shop’s first-aid stations. • Pressurized fluids pose risks to personnel and machinery in the form of burns, fluid injection injuries, and machine fires. • Compressed air systems pose risk to personnel in the form of eye, lung, and internal injuries. • All safety guards and shields should be properly installed on machines to ensure the operator’s safety while the machine is running. • Exhaust ventilation systems must be on and properly connected when a machine is running in the shop. • Fall protection will prevent a technician from falling to the ground when working at elevated heights. • A job hazard analysis (JHA) should be performed before a job is begun. • A recordable accident occurs when an injury results in a fatality, medical care or hospitalization is required, the employee must be absent from future workdays, or the employee’s work is limited. • Wheel chocks should be used when a machine is being unloaded or serviced and when it is parked on a slope. • When entering or exiting a machine, always use three points of contact and face the machine. • Never work below an unsupported implement. Always use implement locks to secure the implement. • Articulated tractors have steering locks that lock the front and rear frames together to prevent the tractor from articulating. • ROPS and seat belts protect operators in the event of a machine rollover. • FOPS protect operators from falling objects. • All heavy equipment machines should be started only when the operator is seated in the driver’s seat with the transmission in neutral and the parking brake applied. • Before towing an implement, ensure the tractor is large enough to handle the size of the implement. • Welding poses a wide range of safety and health risks, including exposure to toxic fumes, burns, eye damage, electric shock, and noise. Proper PPE must always be worn. • Oxyacetylene welding uses oxygen and unstable, highly-flammable acetylene. The welding process generates heat that is high enough to melt metal. Summary Copyright Goodheart-Willcox Co., Inc. Chapter 1 ∣ Shop Safety and Practices 27 Technical Terms acetylene gas automated external defibrillator (AED) backfire burst disk cardiopulmonary resuscitation (CPR) check valve electrocution embolism fall protection falling object protective structure (FOPS) first aid flashback flashback arrestor fluid injection fusible plug implement lock job hazard analysis (JHA) Mine Safety and Health Administration (MSHA) nonrecordable accident Occupational Safety and Health Administration (OSHA) personal protective equipment (PPE) pneumatic system power take-off (PTO) recordable accident recordable incident rollover protective structure (ROPS) rupture disk safety data sheets (SDS) spotter three points of contact unsafe acts welding wheel chocks Review Questions Answer the following questions using the information provided in this chapter. 1. OSHA stands for _____. A. Occupational Safety and Health Association B. Occupational Standard and Health Association C. Occupational Safety and Health Administration D. Occupational Safety and Helping Association 2. The acronym PPE stands for _____. A. personnel protection extension B. personal protective equipment C. personnel protection exam D. personal protective essentials 3. The _____ is required to provide PPE for employees. A. machine manufacturer B. employee C. customer D. employer 4. Of the following, _____ are approved PPE. A. contact lenses B. safety glasses C. sunglasses D. traditional prescription glasses 5. All of the following are examples of PPE, except: A. safety glasses. B. hard hats. C. earplugs. D. neck braces. 6. A _____ fire extinguisher is used to extinguish oil or grease fires. A. Class A B. Class B C. Class C D. Class D 7. A _____ fire extinguisher is used to extinguish electrical fires. A. Class A B. Class B C. Class C D. Class D 8. Heat should be kept away from everything, except: A. hydraulic cylinders. B. solder. C. gas cylinders. D. accumulators. Copyright Goodheart-Willcox Co., Inc. 641 Chapter 19 ∣ Hydraulic Brake Systems Examples of brake fluid boiling points are: • 3 with no water) = 400°F • Wet DOT 3 (with 3.7% absorbed water) = 284°F • Dry DOT 4 (with no water) = 446°F • Wet DOT 4 (with 3.7% absorbed water) = 311°F Note Some agricultural dealerships service ATVs, and some ATVs require DOT 5 brake fluid. DOT 5 is a silicone-based brake fluid that is , non- that it repels of absorbing it. Special care must be taken to from entering the will occur. DOT 5 are prone to a amount of air, mak- ing the fluid more compressible. DOT 5 fluids should not be used in anti-lock braking systems. Caution Handle DOT 3 and DOT 4 brake fluids with care because they will damage A is not careful could harm a machine’s paint finish, causing customer dissatisfaction. Hydraulic Service Brake Control Valves Many late-model hydraulically actuated brakes use a hydraulic pump as the source for the brake along with a The be to the brake or be used for other circuits, as steering, transmission, pilot implement hydraulics. must a positive-displacement pump so it build sufficient pressure to apply the brakes. As mentioned in Chapter 4, Equipment Identification , a positive-displacement pump uses tight seal- ing to produce a constant flow of fluid for a given revolution. as compared to a non-positive-displacement pump, which uses an works on the principle of Non-positive-displacement lose when they encounter pressure, and for that reason, not used for applying brakes. The pump can be a fixed-displacement pump or a variable-displacement pump. A fixed-displacement produces a specific of fluid for each revolu- tion. Fixed-displacement pump a prevent excess pressure building in circuit. A variable-displacement pump varies For decreases the system flow when flow is not needed. A service brake control valve directs pump flow to apply the when the the brake pedal. The brake valve can be located pedal and mechanically it can be included with pedal. Some wheel loaders pedals (right and are through a linkage to a brake Variations of service valve shown in Figure 19-19 are commonly used in and large wheel loaders, wheel dozers, and motor graders. Goodheart-Willcox Publisher Figure 19-19. An example of a foot-operated brake control with separate supply lines. The valve controls both the front and rear brakes. Drain Brak e supply fluid Brak e supply fluid Rear brakes apply fluid Front brakes apply fluid Upper spool Lo wer spool Summary feature provides an additional review tool for you and reinforces key learning objectives. Review Questions allow you to demonstrate knowledge, identification, and comprehension of chapter material. Technical Terms list the key terms to be learned in the chapter. Illustrations have been designed to clearly and simply communicate the specific topic. Cautions alert you to practices that could potentially damage equipment or instruments.