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Toyota FD 150 Forklift Okumura Transmission lack of power

JRK1978

Plastic
Joined
May 5, 2022
Toyota FD 150 15 ton Capacity Diesel Forklift built 1976


Torque Converter Okamura Model Y60871X


Transmission Okamura Model Y88261X

I'm looking for a repair manual for the complete machine or just for the transmission.


machine has almost no power even when Transmission Oil is cold.


as Transmission Oil I use SAE 30W30 which operates a little bit better than 20W20.


Torque Converter has been dismantled and bearings have been changed. no cracks or missing parts inside.


The Control valve and regulator valves are also OK


Does anybody have an idea how to check torque Converter? I can't measure the Pressure cause I don't know where to measure and which Value is ok
 

matt_isserstedt

Diamond
Joined
Dec 15, 2003
Location
suburbs of Ann Arbor, MI, USA
I could be thinking about this wrong but the first thing that jumps out at me is using slippery engine oil instead of ATF = automatic transmission fluid, much closer to a hydraulic fluid, but designed to be "squeezed out" of the friction material.

I don't know what Toyota specifies, it would be good to check that first.
 

JRK1978

Plastic
Joined
May 5, 2022
you are right normally ATF is recommended. but with ATF it is even worse. SAE 30W30 is a trick which I was told from an old forklift guy. he worked with old Clark forklifts and when the Clutch got bad he replaced ATF by 30W30 cause it is a little bit thicker. I have made the same at a Toyota FD 100 10 tons forklift and it works without any problems.but the FD 150 is worse in transmission condition. torque converter and transmission are divided in that forklift.there is a cardan shaft between torque converter and transmission. so when you shift in 1st gear forward and release the brake you see the shaft turning for some seconds. ( machine is standing still as long as the engine is working in idle speed)I assume during that period the clutch is slipping . but after these few second the shaft stops turning . so I think torque converter is also weak
 

BT Fabrication

Stainless
Joined
Nov 3, 2019
i believe most of the clutches inside are common gm transmission size. either way, sounds like it needs a rebuild. and torque converter has clutches in it also.
 

JRK1978

Plastic
Joined
May 5, 2022
yes I expect also that the clutches have to be rebuild but the more important question is where is the problem with the torque converter. it does not have a clutch inside. attached 2 pictures from inside.DSC_2210.jpgDSC_2211.jpgDSC_2210.jpgDSC_2211.jpg
 

JRK1978

Plastic
Joined
May 5, 2022
I fixed it myself. some Oil seals were worn. Air came into the System and this caused the loss of power.
 

john.k

Diamond
Joined
Dec 21, 2012
Location
Brisbane Qld Australia
Common in some dozers.....aerate the converter fluid,zero drive until the air settles out......reason being aerated fluid has much less weight than solid,and a converted is a dynamic device working on fluid density.
 








 
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