Group 34, Uprights
34-2-2 • Troubleshooting SM 765, Nov ’06
Load cannot be lifted to maximum height
• Hydraulic fluid level low, check level and fill.
• Debris in upright; check and clean.
• Hydraulic hose fittings loose or damaged; check
and torque correctly (see Group 40 for specifica-
tions) or replace.
• Check cylinder for external leakage; replace cylin-
der if cracked.
• Cylinder shimming is incorrect; check and adjust
shimming.
• Internal leakage on lift or secondary piston cylin-
ders; remove rod and piston and clean check
valves; also clean and inspect/replace piston seals.
See Section 5.
• Cylinder check valve on lift or secondary piston
cylinders not functioning properly; remove rod and
piston and clean check valves; also clean and
inspect/replace piston seals. See Section 5.
• Hydraulic pump defective; see Group 29 for pump
troubleshooting information.
• Upright rails binding:
a. Perform a visual inspection and check for worn,
or distorted parts, broken or cracked rails or tie-
bars, correct chain and hosing placement and
operation
b. Check rollers for contamination and proper oper-
ation, perform roller clearance check and adjust-
ment
Lift speed sluggish
• Hydraulic fluid level low; check level and fill.
• Broken hoses or fittings; check and repair.
• Pump inlet line restricted; remove from pump and
clean.
• Damaged or binding upright roller; check condi-
tion of roller and replace if necessary.
• Internal leakage on piston-type lift and secondary
cylinders (with load); perform cylinder checks
listed under “Load cannot be lifted to maximum
height.”
• Hydraulic pump defective; see Group 29 for pump
troubleshooting information.
• Defective main lift valve; see Group 30 for valve
troubleshooting and service information.
• Defective velocity fuse; remove fuse from cylinder
hydraulic port, clean and recheck for proper opera-
tion.
• Defective priority valve; see Group 30 for valve
troubleshooting information.
• Defective upright load-lowering flow valve;
remove valve clean, inspect, and replace if neces-
sary.
Lowering speed sluggish
• Damaged or binding upright roller; check condi-
tion of roller and replace if necessary.
• Damaged or kinked hydraulic hose or tube; check
condition of hose and tube, repair or replace as
necessary.
• Defective upright load-lowering flow valve; check,
clean and replace valve if necessary.
• Defective velocity fuse; remove fuse from cylinder
hydraulic port, clean and recheck for proper opera-
tion.
Load bounces excessively when lowering
• Air in hydraulic system, TSU and Hi-Lo ram-type
cylinders; set capacity load on upright and lift form
fully collapsed to full lift height for 10-15 cycles.
• Defective upright load-lowering flow valve; check,
clean and replace valve if necessary.
• Defective main lift valve; see Group 30 for valve
troubleshooting and service information.
• Defective velocity fuse; remove fuse from cylinder
hydraulic port, clean and recheck for proper opera-
tion.
Upright mis-staging (TSU lifting)
• Debris in upright roller area of carriage; check and
clean.
• Interference between carriage and inner rail or cyl-
inder; check staging alignment and adjust or repair
as necessary.
• Bent or broken carriage or inner rail; replace part -
do not try to repair by welding.
• Damaged or binding carriage roller; check condi-
tion of roller and replace if necessary.
• Carriage roller shimming or thrust roller out of
adjustment; perform roller checks on carriage and
make adjustments as necessary.
• Damaged or kinked primary cylinder hose; check
condition of hose, repair or replace as necessary.
• Primary cylinder chain or chain sheave binding or
damaged; inspect and repair.
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