Keeping a Mitsubishi triplex mast lifting square and quiet across the 5M15D to 5M35D forklift truck series takes 38 pages of factory instruction, and Mast Supplement 99739-151T0 holds them for all five models. This Mitsubishi 5M15D–5M35D Series service manual supplement covers the mast only, not the engine or the rest of the truck: removal with the lift bracket, then teardown and reassembly through rollers, strips, both lift cylinder stages, chain and hydraulic lines. Rollers and strips can also come out with the mast left on the truck, and a troubleshooting chart works through load drift, mast noise, chain tension and uneven fork tip height. Set mast strip clearance at 0.1 to 0.5 mm (0.004 to 0.020 in.) and hold main roller to thrust surface clearance at 1.0 mm or less. Night shift, your truck down, nobody to ask. Bookmarked and text searchable, this PDF is yours once bought and stays with your trucks for good.
What's Inside This Mitsubishi 5M15D–5M35D Series Manual
| System | Pages | Key Topics |
|---|---|---|
| Mast System | 7-8 | Structure and Function (Triplex Mast) |
| Mast Operation | 9 | Operation of Triplex Mast |
| Removal and Installation | 10-12 | Mast and Lift Bracket Assembly (Triplex Mast Removal) |
| Disassembly and Reassembly | 13-24 | Triplex Mast (Disassembly, Reassembly, Installing Lift Bracket Rollers) |
| Removal and Installation of Mast Rollers and Strips Without Removing Mast From Truck | 25-33 | Triplex Mast (Chain Tension Inspection and Adjustment, Checking Chain Elongation, Clearance Between Lift Bracket Roller and Inner Mast) |
| Troubleshooting | 34 | Inner Mast Movement, Lift Chain Tension, Mast Noise, Fork Tip Height |
| Service Data | 35-36 | Chain Extension, Main Roller Diameter, Side Roller Diameter, Mast Dimensions, Lift Bracket Dimensions, Finger Bar Bend |
| Tightening Torque for Standard Bolts and Nuts | 37-38 | Nominal Size, Pitch, Metric Fine Thread, Spring Washer Torque |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| Mast strip clearance | 0.1 to 0.5 mm (0.004 to 0.020 in.) | p. 29 |
| Clearance between main roller circumference and mast thrust surface F | 1.0 mm (0.04 in.) or less | p. 29 |
| Clearance G (Lift bracket middle/lower roller) | 0.1 to 0.5 mm | p. 17 |
| Clearance F (Lift bracket upper/middle/lower roller) | 1.0 mm or less | p. 17 |
| Clearance G1 (Side roller) | 0.1 to 0.5 mm | p. 18 |
| Clearance H (Second lift cylinder) | 1.6 mm or less | p. 22 |
| Tightening torque for tilt cylinder socket bolt | 153 to 182 N·m | p. 32 |
| 5M15D, 5M20D, 5M25D | ||
| Tightening torque for Nuts 1, 3 (5M15D/5M20D/5M25D) | 98 +49/0 N·m | p. 27 |
| 5M30D, 5M35D | ||
| Tightening torque for Nuts 1, 3 (5M30D/5M35D) | 147 +49/0 N·m | p. 27 |
Mitsubishi 5M15D–5M35D Series Common Problems This Manual Covers
Mitsubishi 5M15D to 5M35D triplex mast lift bracket and inner mast will not move smoothly
Check clearance between the lift rollers and side rollers, and look for any roller binding. Measure side roller clearance G1 against 0.1 to 0.5 mm per page 18. Then measure mast strip clearance on page 29 against 0.1 to 0.5 mm and adjust any strip that falls outside that range before testing the mast again.
Manual Section: Troubleshooting p. 34Triplex mast lift bracket or inner mast binds when raising or lowering the forks
Inspect side roller clearance first and measure G1 against 0.1 to 0.5 mm. Next, run the chain tension inspection and adjustment starting on page 27 and set lift chain tension correctly. If the binding persists, check the lift cylinder shim adjustment and correct the shims before you cycle the mast under load again.
Manual Section: Troubleshooting p. 34Triplex mast rollers not rotating smoothly and mast making noise during lift
Spin each mast and lift bracket roller by hand and replace any roller that drags or feels rough. Measure main roller and side roller diameters against the service data on page 35. Replace rollers and strips without pulling the mast from the truck by following the procedure on page 25, then recheck roller clearances.
Manual Section: Troubleshooting p. 34Lift cylinder drift: raised load descends on its own while the mast is held stationary
Inspect the lift cylinder packing for wear or damage and replace it if the load keeps settling. With the cylinder apart, check the sliding surface of the lift cylinder tube for scoring, because a damaged tube will chew up new packing fast. Follow the lift cylinder installation steps in the disassembly section starting on page 13.
Manual Section: Troubleshooting p. 34Whole triplex mast shakes and shows play at the mast support mounting
Inspect the mast support bushings and the surrounding metal surfaces for wear. Replace worn bushings and repair any worn metal before the play gets worse. Use the mast removal and installation procedure on page 10 if you cannot reach the bushings with the mast in place, then check bolt torque against the standard chart on page 37.
Manual Section: Troubleshooting p. 34Fork tips differ in height when the forks are lowered to the floor
Check for uneven loading first, then inspect both forks for bends. Measure the finger bar for bend against the limit in the service data on page 35 and replace the finger bar if it is out of spec. Replace any bent fork, then lower the carriage and confirm both tips sit level.
Manual Section: Troubleshooting p. 34Frequently Asked Questions
What are the torque specifications for standard bolts and nuts on the Mitsubishi 5M15D–5M35D Series forklift?
The torque specifications for standard bolts and nuts vary by nominal size and pitch. For example, a 6mm nominal size bolt with a 1mm pitch and a spring washer requires 9.6 N·m (0.98 kgf·m) [7.1 lbf·ft] of torque. p. 37
What is the standard clearance for the lift bracket middle roller on the Mitsubishi 5M15D–5M35D Series forklift?
The clearance G between the middle roller and the thrust plate should be maintained between 0.1 to 0.5 mm (0.004 to 0.020 in.). If the clearance is excessive, it must be adjusted by increasing the thickness of the shims. p. 18
What is the procedure for bleeding the lift cylinders?
To bleed the lift cylinders, start the engine and raise and lower the lift bracket with several strokes. After proper operation is confirmed, check the oil level in the hydraulic tank. p. 12
What is the service limit for chain elongation on the triplex mast?
For the triplex mast, the service limit for chain elongation measured over 20 links is 327 mm (12.9 in.) for the 5M15D/5M20D models, 392 mm (15.4 in.) for the 5M25D model, and 523 mm (20.6 in.) for the 5M30D/5M35D models. p. 28
What is the standard tilt angle for the triplex mast?
The standard tilt angle for the triplex mast is 6 degrees forward and 6 degrees backward. p. 32
How will I receive this Mitsubishi 5M15D–5M35D Series Mast Supplement?
A 38-page Mast Supplement Service Manual in searchable PDF format, available the moment you complete checkout. View on computer, tablet, or phone, with no shipping wait.
Is printing allowed for this Mitsubishi 5M15D–5M35D Series Mast Supplement?
Yes. Print a single page or a chapter for your own shop use, on letter or A4.
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