We have purchased 02 units of UN 03 wheel electric forklifts (FBT16-AZ1). First one was about 10 months back and the other a couple of months back. We are currently faced with a problem of hydraulic system of both the trucks that led us to stop using both of them. Once we start using the trucks, the entire hydraulic system- the hoses, cylinders, hydraulic pump, motor, hydraulic tank are all heating up excessively within about 10 minutes. The heat is felt if one stands near the machine, even the operator can feel this heat from his seat. We have checked hydraulic filter, lines, cylinders, hydraulic pressure and were all normal. We even changed the hydraulic oil of 02 different grades but the problem did not solve. The response we got from UN was not at all acceptable. They don't tell us what's to be done.
Could someone please help us solve this issue ? What is the maximum acceptable temperature of the hydraulic system when a similar forklift is being used ? We can measure the temperature and let you know, if necessary. An urgent assistance / advise is greatly appreciated
Showing items 1 - 17 of 17 results.
Swoop223
Thank you for the comments. Yes, you are right and I also feel it is not too hot get so excited. We did a one more thing and fixed a Japanese cooling fan (a small 48 V one) just near the hydraulic pump and directed the air flow towards it. Seems like it also helps to cool down the pump and motor substantially. We ran the truck for about 04 our after this and the temperature had dropped by about 10%. I am sure this would certainly give us a piece of mind ! We are trying to fix another cooling fan directed to hyd motor. Shall post the outcome over the weekend
well out of all those readings you have there the highest of 58C doesnt seem to be too excessive. But that is only after run for 30 mins. Try running the machine for a bit longer...
lets say 1hr or let it run for half a day and then take readings and see. You'll want to catch it after it has been ran normally and is in the excessive heat stage.
If you are getting overheat errors that is when you want to take the readings... when it is in that state.
The readings that will most likely trigger an overheat code would be on the hydraulic motor itself or back on the control panel where the temp sensors are at.
If you are just concerned because the truck is building up heat , well most electric trucks will get hot after being ran for a long period of time, usually at the end of the battery charge when the battery is in its low charge state is when the heat generated is at its highest because of the high amp draw / low voltage state.
Now if you start seeing temp readings upward towards 70C anywhere that would be excessive i would think.
Dear swoop223
I have taken the temperature readings of the truck after operating for about 1/2 hour and they are as follows; hyd pump 54 C, hyd tank 58 C, Hyd motor 52 C, hoses 43 C, Side shifter 38 C, lift cylinder 51.6 C.
on the rated temp of the hydraulic oil in the system i would think it should be something around this:
[Oil temperature 45C (113F)]
it may vary somewhat but that's the general range it should probably be at. I wouldn't want it to exceed that by too much.
once you get some readings from the truck post them back here.
Dear Swoop223
No special attachments on this truck but has side shifter and a special size of forks (170 mm width x 1070)
Dear RCAV8TOR, this truck is being used at a biscuit manufacturing facility both in the warehouse and manufacturing.
Addy, Edward, Swoop223- Wish you all a very happy new year and extremely sorry for my delayed response as I was out of the country. Just returned. I went through your replies from overseas but could not respond as I did not have my password with me to post a replies. Sorry about it.
During my trip I purchased an infrared industrial thermometer and intend checking the temperature tomorrow morning and inform you'll the same. What is maximum acceptable temperature of the hydraulics of a forklift when it has run for a considerable period ? than Its very strange that this truck has only 01 hydraulic filter which is the in line filter and there is NO return filter. When enquired from UN they response was- this model has only 1 hydraulic filter. We changed the seals of the pump too but the problem remains the same. UN has finally sent us a warranty pump and a motor, which we intend installing tomorrow. Shall keep you posted on the outcome
good suggestion edward
a handheld infrared heatgun (very common and inexpensive)
run the truck and monitor the components as it is heating up
see where the 'hotspots' start and you should be able to narrow this down fairly easily.
It is even possible that the return filter (usually in the hydraulic tank, these days) is blocked causing restricted return to tank flow. When you say you checked the filter and it was normal, could you go into how you checked it? If it was me, I would change it to a new filter to insure it was normal.
An infrared heat temp measuring gun should make this a lot easier to troubleshoot, running the pump and shooting the components to see where heat is first being generated.
I would also check to insure no air is being drawn into the line from the hose that feeds the pump from the reserviour, by looking for foam in the hydraulic oil reservoir.
I would be seriously surprised to find any 'improvements' in the mast or lift cylinder size to have any effect in heating, in fact, I would expect it would be contrary, where the larger surface area would dissipate heat from the oil even quicker, with slightly slower lift operation. unless the -pressure- is different.
Are you positive that the pump is not running at speed when it should not be? Does the hydraulic pump "ramp up" when the demand increases, like when lift is selected?
Possible unload valve not operating properly. What application is this truck used?
Did you check the motor temperature as well? Considering a latest truck i hope AC motor is in their to drive the pump. If motor us heating up as well then disconnect the pump and check the motor Amps with and without load. There is a possibility that motor has faulty bearings which are causing this. If motor is normal then In such situation i will go for a pump service first. I doubt if Pump seal kit is still alright with this excessive heat.
Thanks a lot Addy. We in fact did this. The lines are connected like this. hyd tank to pump and pump to steer system and control box (one line divided to 02 via junction). What we did first was removed the delivery line from pump to steer system and control box right at the beginning from the pump out, which is one line at the beginning and connected a hose and let the hydraulic delivered back to tank without connecting to any other delivery lines. We ran the pump for about 15 minutes. Both the tank and hydraulic oil became excessively hot again. Have either the hyd pump or motor become faulty or have both become faulty ?
I seen this problem with bendi and found steer control valve faulty. you can diagnose in steps as below.
let start from control valve and pump itself. remove all connections from control valve including steer connections. run the hydraulic motor, oil will go back to the tank via control valve return system. run fro a while and not the temperature.
on the next step connect the steering hoses only, run for a while and note the temperature.
remove steer and connect the tilt system. run for a while and note the change in temperature.
now connect the lifting hoses and check it as well.
it is bit lengthy but you would be able to find out what exactly the problem is. You may do it once battery in the forklift and once putting battery out side.
keep posted the TS details.
Regards,
Addy
Thank you RCAV8TOR for your inputs
Unless they are dead heading the hydraulics when running, i would probably check if problem is possibly from power steer system
Dear Swoop 223
Thank you for the response. UN does not take the issue seriously in spite of my repeated requests and telephone calls. I even agreed to bear all costs of an engineer's visit to Sri Lanka. They are refusing to send an Engineer. Both machines are under warranty. It is a shame on UN !
It is NOT the battery that causes the heat generation and is actually the hydraulic system that generates the heat. Based on the specs of the first truck we ordered the 2nd truck and when it arrived we noticed that the mast and tilt jacks of the 2nd truck are fairly bigger compared to the 1st truck. When this was informed to UN the answer was that they had improved the masts. But I personally feel the mast of 2nd truck is oversized and it probably could be mast fitted to a truck of higher capacity and it may create a strain on the hydraulics. My question is why the first truck too developed the same problem ? No attachments are fitted except the side shifter. Hose sizes, number junctions can check and let you know. UN is also sold in U S. Do you know the distributor in U S and can we get some advise from them if they have faced with a similar situation ?
are you using attachments on these lifts?
bale, carton or barrel clamps?
rotators?
attachments are well known for causing undue strain on hydraulic systems and will cause extra heat build up after a short time if the unit is used frequently.
The size of the hose and how many junction fittings are used
Every place there is a fitting or a junction is a restriction and causes friction in the oil which will create heat. The extra strain on the pump will also create excess heat buildup.
What size is the hosing going to the tilt and lift after the control valve? How many junctions are there in this.
One other thing to consider is... is the heat actually being generated by the hydraulic system? or is it being translated from the battery through the frame, the battery being the problem and not the hydraulic system? It could be both the battery AND the hydraulic system combined creating this 'heated' situation.
There are many things to consider and from what it sounds like you need to get the factory engineer's to come evaluate this condition if the truck is still in warranty. It is their responsibility as the manufacturer to resolve this issue for safety reasons if anything...
a fire on an electric truck due to heat and an engineering design flaw is not a good thing. They should consider this possibility first and foremost. Trust me... i have seen fires start this way and burn a truck up... They should be concerned and do something about it. :o)
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