This document discusses the daily activities of a vehicle maintenance department at Mt. Bachelor. It describes maintaining hydraulic systems for snow grooming machines, including drive pumps, auxiliary pumps, control systems, and making adjustments. It also covers recovering equipment when failures occur, such as torque hub bolts backing out or hydraulic systems leaking. Equipment repairs include welding cracks and failures using various welding processes, as well as repairing a cracked splitter box lid and bearing seat.

1. A DAY IN MAINTENANCE
FLUID POWER
WELDING REPAIR
MT. BACHELOR
VEHICLE MAINTENANCE DEPARTMENT

2. HYDRAULIC SYSTEMS
• Prinoth (CAT) and PistenBully (Cummins) Machines
• Rexroth and Sauer Danfoss Drive pumps (Swash Plate Design)
• Hydrostatic system (Piston Pump)
• Drive motor to torque hubs
• Auxiliary pumps (External Gear Pump)
• Volumetric Displacement varied by machine/subsystem flow requirements
• Commonly around 3000 Psi (relief valve adjusted)
• Control Systems (HDP/CAN bus)
• Hydraulic Digital Processor (PLC)
• CAN bus (PistenBully)

3. • Control Center
• Fine tune system/subsystems
• mA adjustments
• Drive Pumps (hydrostatic system)
• Drive pump centering crucial to
ease of system start up and
component life
• Auxiliary pump(s) for hydraulic
system(s) piggy-backed off of
secondary drive pumps

4. • Capstan style Winch
• Cable Fray detection sensor(s)
• Proximity switches
• 360 deg. Boom pivot
• Pulling force relative to up-hill and
down-hill motion and system load.
• System design are dependent
on manufacture
• Potentiometer controlling servo
piston position, changing the swash
plate angle, thus piston stroke is
increased/decreased
• Some of these system are more
complicated with the addition of
winches and tillers, relative to

5. EQUIPMENT RECOVERY AND REPAIR
• Everything mechanical will eventually fail
• Equipment recovery tends to be complicated
• Concerns are:
• Potential for personally injury increases.
• Potential for increase in property damage.
• Equipment down time/loss of production.

6. • Most complicated recovery I was responsible
for
• Torque hub bolts backed out
• Twisting drive hoses
• Hydrostatic system leaking
• Hydraulic system compromised

7. • Winch boom used to remove Tiller in
order to open track and began
repairing system.
• Team work was key to this recovery
• Support from Director of Maintenance
was greatly appreciated.

8. EQUIPMENT REPAIR
• Standard welding processes performed
• SMAW 7018 and 6010
• GMAW ER70s
• Arcair
• Oxy Acetylene
• Tig SS and Al

11. • Fan drive hub welds failed
(75%)
• Longitudinal cracking
• Miss alignment/adjustments
of subsystem aided in these
welds failing.

12. • Splitter box lid cracked
• Damaged Bearing Seat
• Repaired crack (TIG) bored new seat
• Turned spacer, grooved and drilled to match oil passages
on self-centering bearing
• Pressed in spacer to new seat and re-assembled box.

13. • Hose routing sometimes creates
problems that lead to larger
problems
• Many components needed to be
replaced modified or repaired.
• Some hydraulic hoses can be built
in house.
• Assorted JIC fittings available
• Specialty hoses/drive hoses are
special order from
manufacturer