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Technical Info Archives

Forklift Hydraulic Pump Failure

forklift hydraulic pump failure

System contamination is a leading cause of forklift hydraulic pump failure. Hydraulic repair is an important process to do to improve your equipment’s longevity. There are multiple causes for system contamination including:

  • Improper fluid flushing after repair
  • A non-thorough cleaning job is performed
  • Technician does not remove contaminants from hydraulic system
  • Technician cannot see the oil cleanliness level before or after repairs

Phases of Wear

Wear on a lift truck begins as soon as it is put into use. Some wear can be identified through regular maintenance checks, while other wear may not be noticeable until later. As a lift truck gets older, it may show signs of wear during routine maintenance. Oil analysis can help identify potential issues. At this stage, it may be possible to keep the lift truck operating normally by addressing the wear. However, if too much wear has occurred, it may be necessary to replace components or perform an overhaul. The task of a service technician is to monitor the lift truck and make any necessary changes when wear or contamination is detected, using regular maintenance practices and tools like filter caddies. An effective oil analysis program should allow for early detection of issues that may require a flush, allowing for a simple oil change rather than a more extensive procedure. The success of this detection depends on taking oil samples at the right intervals and using appropriate laboratory tests.

Phases of Wear Table

As Time Progresses
Operating NormalOperating NormalSome Symptoms AppearPerformance IssuesFailure
Non Detectable WearSome wear detectable through fluid analysisPoint of no return
Visible wear, changes in behaviorVery visible symptoms and wearForensics
Objective is to increase the operating time with non detectable wear through standard maintenance practices, including conditioning units (filter caddy) and an oil analysis program.
forklift hydraulic pump failure

Causes of Hydraulic System Failure

According to industry data, a forklift hydraulic pump failure, which occur at a rate of 70-80%, is likely not due to design issues, but rather to contaminants such as water or lubricant degradation. These contaminants can be introduced through various means, including improper maintenance and service procedures, the addition of fluids, the replacement of failed components, and dirty equipment or parts storage. Contamination can also occur due to ingression, such as through leaky cylinder seals or poorly maintained reservoir vents, as well as due to internal wear and part failure. Additionally, chemical reactions between lubricant additives, water, air, heat, and metallic particles can also contribute to contamination.

Contaminant Caused Hydraulic System Failure

When there are high levels of contaminants in a hydraulic system, it can lead to wear on all moving parts and erosion of soft metals. Chemical reactions between additives and water or incompatible oils can also cause etching, which reduces pump efficiency and increases the likelihood of internal leaks and high temperatures. High temperatures can reduce the life of oil additives and impair the lubricant’s ability to separate moving parts, and metallic particles can contribute to the rapid oxidation of the lubricant. This destructive process can result in the failure of major components, such as pumps or cylinders, and when a failure does occur, it can release millions of metallic particles, fibers, and contaminated oil throughout the system. Simply replacing the oil in the reservoir is not enough to fully restore the system.

Double Oil and Filter Change

This process is intended for lightly contaminated systems or those with degraded fluid, and should not be used for systems that have experienced major component failures. It is worth noting that replacing a large volume of oil and disposing of contaminated oil can be costly, and if the oil is not degraded, this would be a waste since it is only contaminated and not degraded. To “condition the fluid” by removing particles and water, a filter caddy can be used.

This process involves an initial oil drain and filter change to remove a significant portion of contaminants and degraded fluid. The system is then filled with pre-filtered oil and the fluid is circulated at low pressure until it reaches operating temperature, each hydraulic function has been operated three full cycles, and the fluid has been turned over at least five times. The oil is drained again, the system is refilled with filtered oil, and the filters are changed a second time. After the fluid has been circulated, each circuit has been operated three full cycles, and the system has warmed up to operating temperature, an appropriate oil sample should be taken to evaluate the success of the flush.

forklift hydraulic pump failure

Mechanical Cleaning

When a forklift hydraulic pump failure or cylinder failure has occurred, it is necessary to include mechanical cleaning as part of the flushing strategy. This involves using a pneumatic projectile gun and sponge projectiles to clean tubes and hoses, as well as disassembling other components for cleaning using brushes and clean solvents. It is important to also mechanically clean the reservoir to remove any residual contamination particles. While mechanical cleaning can be labor-intensive, it is the most effective way to restore the system to reliable operation after major mechanical failure.

Component Cleaning Process

Reservoir Cleaning Process

  1. Ensure absolute cleanliness in all of the following procedures.
  2. Clean the top of the filter housing, cap, and surrounding surface to avoid adding extra contaminant.
  3. Remove the filter housing cap, filter element, and element bowl to allow access to the interior.
  4. Use a filter caddy to pump the fluid from the reservoir to a storage container to dispose of.
  5. Remove all remaining oil from reservoir.
  6. Remove and get rid of the suction strainer.
  7. Remove and get rid of the reservoir breather.
  8. Clean the reservoir to remove all contaminants.
  9. Clean all accumulated metallic particles from the magnetic plug and reinstall.
  10. Install new reservoir breather.
  11. Install new suction strainer.
  12. Cover the reservoir openings until ready to perform flushing operation.

Cylinder Cleaning Procedure

  1. Ensure absolute cleanliness in all of the following procedures.
  2. Clean the external surfaces using industrial, residue free wipes prior to loosening fittings and components.
  3. Cover all connecting hose and cylinder openings immediately with caps to prevent dirt and debris from penetrating the system.
  4. Disassemble the cylinder and clean all parts with filtered petroleum based solvent to remove all contamination particles. Ensure that you clean the seal grooves, gland nut, and port threads.
  5. Install new seal kits.
  6. Fill the cylinder with filtered hydraulic fluid. This will displace the air and reduce the risk of air compression in the cylinder that can cause dieseling during initial pressurization at start up. Dieseling will result in damage to the cylinder and seals.
  7. Plug all ports and reinstall into the equipment.

Post by Intella Parts Company, LLC

How Do I Measure my Bobcat Skid Steer Tracks

Rubber track dimensions are important to finding the proper rubber track for your equipment.

Product shown: 450X86X58. This product is used on Bobcat T870, Bobcat T830, Kubota SVL90, Kubota SVL95 and more.

Question: How do I read rubber track dimensions?

Answer: Rubber track dimensions are read as width (mm) x pitch (mm) x link (total number of links in the track).

Question: How do I measure my rubber track dimensions?

Answer: the track width is simply the width of the track. The pitch length is the distance between two links. The links are all of the crests that surface from the rubber.

To see an outlined diagram of rubber track dimensions, see the diagram below:

rubber track dimensions

Need Rubber Tracks for your Equipment?

Intella Parts offers a wide range of rubber tracks to satisfy your equipment’s needs.

Give us a call at (616) 796-6638 or email us for any inquiries.

Post by Intella Parts Company, LLC

Dana Off-Highway Transmission Oil Specifications

Dana (also known as Clark) off-highway transmissions are used in a variety of different forklift brands.  Dana actually purchased the Clark division back in 1997 (over 20 years ago!) but the name Clark still lingers on.

Need Dana or Clark transmission parts? We can help – just click here

Recommended Lubricants for Dana/Clark Transmissions and Converters:

  • Preferred Oil Viscosity

    • See the chart below and base your lubricant based on the correct temperature
    • If more than one applies, pick the one that your temperature is closest to the middle in the range


      Oil Application Chart
  • Approvals: Make sure to use multi-viscosity lubricants
  • Not Approved: GL-5 and engine oils – use only lubricant specified for transmissions!
  • Sump Pre-Heaters: Transmission fluid needs to be heated to a specific temperature before use to make sure it is pumping with the correct viscosity.
  • During warm up, make sure to stay in neutral gear! Driving is not allowed with a full load until minimum sump temperature is reached.
  • Using synthetic fluids, oil service life may be longer. To determine each transmissions change interval, measure the metal wear and oil oxidation over time to figure out the baseline. Please remember that removal of the transmission based solely on checking the metal ware is not recommended.
  • Transmission lubricant should follow the specifications of one of the following:
    • Caterpillar TO-4
    • MIL-PRD-2104G
    • John Deere J20 C, D
    • Dexron IID or Dextrol III

Need complete transmissions? Head over here!

Need spare parts? Click here!

Need TCM Forklift parts? We have them too!



Series TE-13
Series HR-28
Series FT-08
Series TE-10
Series TE-32
Series HR-32

Post by Intella Parts Company, LLC

Axle tech Forklift Parts

Need Axle tech forklift parts?  Intella can help you out!  Axletech parts are used in a variety of different forklifts.  Axletech supplies axles and differentials to forklift brands such as Hyster, Taylor, Kalmar, Yale, and ground support equipment such as Tug.  Axletech mostly supplied drive axles to the forklift industry but they also supplied forklift steer axles for a few manufacturers.

Intella is your online source for Axle tech forklift parts.  We offer the complete Axletech product line!  We’re located in Holland, Michigan and if we don’t stock the Axle tech forklift part you need, we can get parts quickly from Axle tech’s warehouse in Troy, Michigan.

Axletech was formed in 2003 as a spinoff from Rockwell International.  Axles built before 2003 were branded as Rockwell.  If you’re looking for Rockwell forklift parts, search no further.  Axletech is the present-day name for Rockwell.  Axle tech forklift parts also are made in Axle tech’s factory in France.  Our European parent company, VanGent Forklift Parts helps us with  logistics in the event we can’t find an Axle Tech part in the United States.  We have two day shipping service anywhere in the USA or Canada for any Axle tech forklift part we need to obtain from sources in Europe.

Ready to order?  Click here to explore our selection of Axle tech forklift parts.

Post by Intella Parts Company, LLC

Forklift 101: How to Charge a Forklift Battery

Note: Click here to find forklift battery chargers for sale.

10 important things to know when using your forklift charger

1. The ampere hour rating should be within 10% of the forklift battery that is being charged.

To be sure, find the model number of the forklift battery. This will help determine the ampere rating. The battery model number is consists of three things: Cells, amps per cell, and plates, listed in that order.

To come up with the total amps you first subtract 1 from the number of plates (the 3rd number in the batteries model number) and divide that by 2. Then, multiply that by the amp per cell, or the 2nd number in the battery model number. This is the ampere hour rating. In other words, (P – 1)/2 * A = ampere hour rating.

how to charge a forklift battery2.  Inspect the battery charger cables before connecting the forklift battery.

Ensure the battery charger cables do not show any heat damage or damage of any other kind. Heat damage on cables can be an indication of a mismatched charger or that the forklift battery is not performing as it should. In addition, if you see that the cables are frayed, it is very important to have them repaired.

3.   Ensure the charger is the correct size for the battery you are trying to charge.

This is pretty easy to remember. For example, a 24 volt pallet truck charger is made to charge a 24 volt battery. If you are unsure of the voltage of your forklift battery, count the cells or the squares on the top of the battery and multiply that number by 2.

If you have multiple chargers of different voltages, use different connectors for each voltage of the charger so that you can easily pick the correct charger in a hurry. In general, a red connector is used for 24 volts, a gray one is used for 36 volts, and a blue one is used for 48 volts.

4. Never charge your forklift battery if it’s too hot or cold.

If your forklift battery is too hot to touch, you should wait until it cools to hook it up to a battery charger.  Use the same rule of thumb if the battery seems too cold, waiting until it warms up to room temperature before you charge it.

how to charge a forklift battery - forklift charger5. Water your forklift battery on a regular basis.

Make sure to use distilled water to cover the plates in the cells. The plates inside the cells should be fully submerged. If they are not, the cells will quickly lose their ability to hold a charge.

6. Keep a log every time you water your battery.

This way, if you ever have to make a claim while your battery is still under warranty, you will have the log to support that you took proper care of the forklift battery.

7.  Don’t water your forklift battery before charging it.

Never water the battery before you charge it. If you overfill the battery, it can spill sulfuric acid during the charging process. Always fill your battery after it has been charged.

8.  Allow the forklift battery to charge fully.

Make sure your battery undergoes regular full charging.  Partial charges will only reduce the standard capacity of your battery.

how to charge a forklift battery - lift truck charger

9. Charge the battery in a well ventilated area.

Charging a forklift battery can produce hydrogen and oxygen gas, and you do not want this mixture to become concentrated in a poorly ventilated room. Such a mixture is an extreme explosive hazard that must be avoided.

10. Charge your forklift battery after each shift.

Never store your forklift battery on a low charge. This could cause the battery to sulfate. If charged and watered correctly, a forklift battery should last you for many years.  Are you using an older style Hobart battery charger?  You  might consider an upgrade with the newer chargers available from Intella.

Click the button below to shop all forklift battery chargers.

Post by Intella Parts Company, LLC


Electric Forklift Batteries

Forklifts may use several different types of batteries. Electric forklifts require the battery to operate, while gas powered forklifts need a battery to start. Over time, these batteries will run down. Electric forklifts will need to be charged periodically, while other types of forklifts will need the battery completely replaced when it runs down. Replacing these batteries is done in much the same manner as a battery on an automobile, so we will focus more on maintaining batteries in electric forklifts.

What Makes Up the Battery?

An electric forklift battery is made up of five different parts. Those who work on an electrical forklift should know these parts to avoid getting shocked or, worse, causing the battery to explode.

  1. 1.  The battery cells – the battery is divided into different cells, each of which contains a set of positive and negative plates. The plate at each end of the cell is negatively charged, and plates alternate throughout the cell. The number of cells determines how many volts the battery produces.
  2. 2.  Separators – each of the positive and negative plates is separated by a separator, which provides the insulation.
  3. 3.  The battery tray – this is the container that holds the battery cells. It’s usually made from steel.
  4. 4.  Electrolyte solution – everything inside each cell is submerged in an electrolyte solution made of sulfuric acid.
  5. 5.  Element – the top of each cell features an element made up of one positive and one negative terminal. The positive plates are all connected to the positive terminal, while the negative plates connect to the negative terminal.

Forklift Battery Maintenance

How Can you Select the Best Battery for your Forklift?

One factor in deciding on the best battery for your forklift is to look at its size. Larger forklifts that are rated for lifting larger loads are going to need bigger batteries because they will require more power. Smaller forklifts won’t have as much weight to move because the frames are usually lighter, plus they’re not rated for lifting really heavy loads. Another very important factor when selecting proper battery size for your forklift is weight. In an effort to save money, it may be tempting to purchase a smaller battery. Minimum battery weight is listed on the data tag located on your forklift. It is very important to fit a battery that meets these weight requirements. The battery is factored into the counterweight and crucial to the lifting capacity and safety of the forklift. Make certain you get the correct size battery for your forklift.

Before purchasing a new battery it would be wise to have the battery inspected by a battery technician. Often these batteries can be repaired. It may be a matter of replacing a cell or two. It may just need an acid adjustment. These remedies to not make your battery new again but can in some cases extend the life by a few years.

Be careful when buying off-brand batteries. Yes, they may work in your forklift, but they may also be cheaper for a reason—many off-brand batteries are of a lesser quality and will not last as long as the more expensive brand names. Look for product reviews before you make a purchase.

Tips on Charging the Battery

Maintaining a proper charge on your forklift battery is important. If the battery isn’t properly charged, it will run down much more quickly, and then you’ll end up spending more money on replacement batteries than you should. Here are a few quick tips on charging your batteries to make certain you get the most out of them.

  • •  Recharge your battery when it has about 20 percent power left, not before. Recharging a battery when it has more power may damage the battery and shorten its life.
  • •  You don’t have to charge a battery daily—if it’s not run down, don’t charge it. Most forklift batteries are designed for a certain number of charge cycles (1,500 or more). If the battery doesn’t need to be charged, don’t waste one of these cycles.
  • •  To make sure the battery is performing at its best, use the equalize, weekend, or weekly charge setting (the term varies from brand to brand) once every five to ten recharge cycles. This will help ensure longer battery life. However, don’t use this setting too often or you may damage the battery. You may want to keep a log of when these special charge cycles are done to help with this.
  • •  You’ll also want to keep a log of when water was added to the battery. New batteries will need water added to them once every ten charges for the first couple of years in use. After that, or if you’re using a reconditioned battery, you may need to add water to it after every five charges.
  • •  Add water after the charging cycle, never at the beginning of a cycle.
  • •  Don’t interrupt a charge cycle. Doing so will waste one of your charge cycles, plus it can damage the battery.
  • •  If a battery does run completely down, be sure to recharge it as soon as possible. Don’t let it sit for a long period of time.

Steps on Replacing the Battery

On average, a battery for an electric forklift will last around five years, less if it’s used and recharged a lot. Under ideal conditions a well maintained low usage battery can last as long as 10-12 years. Fortunately, these batteries are fairly easy to find, and most are reasonably priced.

There are a number of signs that your forklift battery is about to expire. Here are a few of the most common:

  • •  It doesn’t hold a charge for long
  • •  It needs recharged several times during the day
  • •  The battery case starts to show corrosion buildup
  • •  The battery begins to smell
  • •  The battery begins to smoke while in use or when charging—replace this battery immediately!

Replacing a forklift battery is not as simple as replacing other batteries. The first issue is that the battery can weigh several thousand pounds. It’s going to take another forklift to move it. It can also be very dangerous as batteries carry high amperage that can be deadly if not handled correctly. In many cases, it’s easiest to simply have a battery technician do the installation. These professionals have been trained in forklift battery replacement and can handle everything.

However, if you’re going to do the replacement yourself, you should first make certain that you keep the top of the battery clear of all metal objects. Otherwise, the battery could short circuit and explode. You should remove any jewelry you’re wearing such as a wedding ring—even that small bit of metal can cause an arc. Even keep the connector cables away until you’re ready to connect it. Keep them out of the way, and make sure they’re not going to get caught under the battery.

Now move the new battery under the hoist using a second forklift. Make certain the hoist hooks are securely connected to the battery’s lifting hole. Lift the battery up, carefully move it into position, and then lower it into the forklift. Connect the connector cables and power up the forklift to make certain it works.

Post by Intella Parts Company, LLC


Replacing forklift fuses

My electric forklift doesn’t run!   Could it be a forklift fuse? Often this is the case. Let’s look at how to check your forklift fuses.

Step one:

Disconnect battery from forklift and discharge capacitor.

Remove covers to gain access to fuse panel.   Control fuses are sometimes found under the dash.  These will be Glass tube or blade type fuses.

Most electric forklift fuses are found in the area of the contactor or control panel. You will also find larger power fuses (35 to 500 amps).  Below is a picture of fuses in a standup Yale ESC40-FA forklift.  You’ll see the fuses this truck uses are ANN80 fuses.

Here are photos of other types of forklift fuses you may encounter on electric forklifts.

Visually inspect forklift fuses looking for signs of heat (melted or discolored connections). If you have the glass fuses or fuses with a window you may be able to see an open or damaged fuse.

If you have access to a multi-meter (VOM), there are multiple methods to test your forklift fuses. You can test using continuity mode or resistance mode. You must remove fuse from circuit in order to properly test using this method. You are looking for no resistance.

In rare cases a fuse may pass the visual test and continuity test but may still be the faulty. Forklift fuses can sometimes have enough capacity to show continuity but will not carry current loads. The best method to test a fuse if you suspect this to be the case is to check for voltage. This can be dangerous if proper care is not taken. Be sure to block forklift so that it cannot move if drive circuit is energized unexpectedly. You must first plug in the battery. Always use care when working with live circuits. Locate the common negative terminal. Easily found by following the negative cable from the battery connector the first connection point on the forklift. Keep in mind that electric forklifts are not chassis grounded. Connect your negative lead from your VOM to this terminal. Now probe your fuses on both the supply side and the load side. You should get a reading that closely matches the voltage of your forklift battery at both points. For some control fuses you may need to turn the key on, sit on seat and release park brake in order to energize the circuit prior to testing. If you get the proper voltage reading on both sides of the fuse, the fuse is probably not the cause of the problem.

If you want to test the fuse even further you can test it under load. Be careful this can be dangerous if not done properly. If you do not feel comfortable please do not proceed. Fuses are inexpensive. Replace the fuse if you still suspect it is causing problem. If you work carefully, perform proper blocking methods, and be sure to have a clear working area you can energize the circuit and check voltage on load side of fuse. If voltage goes away when circuit is loaded, replace fuse.

Always replace fuses with the proper type, value and size. Improper fuses can cause extensive damage to other forklift components.

Keep in mind that if you find a blown fuse you should determine the cause to prevent further failures. Often power fuses are damaged from overloading such as pushing loaded pallets along the floor. If this is the case your forklift is working properly and some training is in order for your operator.  If the operator is not the cause you should look for a shorted circuit or component that has caused the failure.  See “How to check for shorted or open circuits

Once all connections are made replace covers and reconnect battery. Test operation.

Congratulations! You have successfully repaired your forklift.

Post by Intella Parts Company, LLC



So your forklift won’t move, where do you start?  Here are some basics in understanding electric forklift diagnostics.  Whether your forklift is electric powered or engine powered the problem could be your forklift electrical system. In this article I will explain the basics of electrical forklift diagnostics.

Because electricity is not visible, it is not easy to diagnose. Compounding the problem is that electrical schematics and diagrams can be confusing. I will try to equip you with the tools needed for proper diagnosis. A technician has to rely on those tools to show where electricity is, or where it isn’t, and then draw accurate conclusions from that knowledge.

If you can learn to “think” like electricity and skillfully use your multi-meter. With an understanding of some basic electrical principles you can then apply them to testing electrical systems.

Have you ever witnessed a technician spending time looking at wiring diagrams or drawing sketches on a piece of paper. He was actually diagnosing the problem at hand. A big part of electrical forklift diagnosis is done at the bench before ever lifting a wrench. A multi-meter (VOM) is the second most useful tool in your arsenal after your brain.


Computer controlled systems offer another complexity to the way electricity works. It is easy for technicians to replace a control board, often because they don’t understand what it does or how it works. This often results in unnecessary expense and can also cause the new part to be damaged because the original problem was not corrected.

By understanding what a control board needs in order to function properly and then ensuring that it has everything it needs to do its job, a technician can successfully determine whether the board needs to be replaced.

OK, so let’s get started. A simple understanding of electricity and basic terms is in order.

What is VOLTAGE?

Voltage can be thought of as electrical pressure. Voltage is the force that pushes electrons along an electrical conductor. The measurement for voltage is called the volt. There are two types of voltage: alternating current and direct current. In forklift circuits we are use both direct current and alternating current.

Direct current voltage (DC voltage) is voltage that is applied in one direction all of the time. Most forklifts use direct current to get their jobs done. Industrial forklift batteries or automotive type batteries supply direct current to the electrical circuits.

Alternating current voltage (AC voltage) is voltage that is applied in both directions in an alternating fashion. This is similar to the electricity found in the electrical outlet of your house wiring.

Some modern forklifts use AC powered motors as they require less maintenance and can be more efficient than their DC counterparts.

What is CURRENT?

Where voltage is the driving force in an electrical circuit, current or amperage is the measurement of how much electricity (electrons) is flowing in a circuit.

We measure current in amperes (amps). Current is the quantity of electrons passing a single point at any given time. Current can be measured in both AC and DC circuits.


Resistance is the opposition of flow in an electrical system. This is sometimes built into the circuit for various functions. All loads create resistance that is normal in a forklift circuit. Resistance can also be caused by lose connections, faulty components and faulty wiring. Understanding resistance can be a key component in understanding how to diagnose electrical circuits.

Resistance is measured in OHMS Ω.

How can we see these different parts of electricity? Using a VOM we can measure the existence of voltage, amperage, and resistance.

To measure voltage; place the black lead of your meter in the com jack of your meter and place the red lead in the V jack. Now adjust the meter to AC or DC depending on the circuit you are testing. Set the meter on auto range. If your meter does not have this functionality, you should set the meter to the highest voltage that you expect to be reading.

There are two types of voltage measurements that are useful in forklift diagnosis: available voltage and voltage drop.


Available voltage is voltage that is present at any given point in the circuit. You can measure available voltage by placing the red meter lead at some point in the circuit (switch contact, fuse, connector, etc.) and the black meter lead on a common terminal. This test will tell you how much voltage, or electrical pressure, is present to do some work at a given point in the circuit.

The available voltage test is good for determining if you have voltage present, but it does not do much in the way of diagnosing what is wrong with the circuit.

Available voltage is a good test to use when you want to see whether voltage is present at a point in the circuit or not. You can think of the available voltage test as a “go, no go” type of test.

Do not use the available voltage test to determine whether a circuit is functioning properly or not. There may be voltage present at a point in the circuit, but that does not mean that the circuit has what it needs to work.


The second voltage test while performing electric forklift diagnostics, and by far the most useful, is called a voltage drop test.

We say that voltage is “dropped” when some form of load uses all, or a portion of, the voltage available.

Loads come in the form of motors, solenoids, contactors, lights, etc. Corrosion, open circuits and damaged contacts can also be considered loads on the system as they can cause voltage drop also. When a load of this type “uses up” or drops voltage, then it may not leave enough available voltage to the rest of the circuit for the circuit to work properly. A voltage drop test will help you to isolate where voltage is being dropped, or used up.

Unlike resistance measurements where the circuit is not turned on, a voltage drop test is performed with the circuit working or turned on.

To perform a voltage drop test you must place the meter leads at two points within the circuit. Remember, during the voltage available test we place the leads at one point in the circuit and the other to common. In the voltage drop test, both meter leads will be placed in the circuit.

With the meter leads placed in the circuit, you are now measuring how much electrical pressure, or voltage, is present between the meter leads. If you measure any voltage at all on the meter display, then there must be some sort of load between the meter leads.

Your next job is to determine whether the load that is represented on the meter display is a load that is supposed to be there, or whether it is a load that may be harmful to the circuit. Remembering a few simple rules will allow you to determine if the voltage drop you are measuring is “normal” or not.

A meter reading of less than 0.1 volts represents a wire, or switch that is operating normally.

A meter reading of full source voltage represents all of the available voltage being dropped. This could be due to an open wire, or it may be a “normal” load that happens to be the only load in the circuit.


The third measurement that can be useful in electric forklift diagnostics is the measurement of current, or of how many electrons are flowing. Current is measured in amperes, or amps for short. Like the voltage drop test, an advantage of measuring current is that the circuit will be performing its function, making this a “real world” test.

The technician must first determine what current or amperage draw is normal for the component or circuit he or she is working on. Current specifications for even common circuits can be hard to come by. If specifications are not known they can sometimes be found printed on the component as on a coil or motor. You can also compare to a known good component.

The second drawback to testing current during electric forklift diagnostics is in that the meter must be installed in series with the circuit you are testing. Since current measurements are actually measuring how many electrons are flowing in the circuit, all of the electrons in the circuit must pass through the meter. This means that the meter must become part of the circuit. An ammeter must be installed in series with the circuit, at a location where the maximum current within the circuit will flow through the meter. This involves opening the circuit up and connecting the meter leads in series with the circuit.

There are a number of good locations for opening up a circuit up to install the meter while performing electric forklift diagnostics, with the most popular, and often the easiest, being at a circuit fuse. This is done by removing the fuse and installing the meter leads on either side of the fuse connectors.

The third drawback to using current as a diagnostic tool is that you may not know how much current is flowing before you install your meter. The current flowing is often more than what your meter can handle. Although a quality meter is fused, often these fuses will blow when trying to measure current because the circuit being tested uses higher current than what your meter is designed for.

To get around these last two drawbacks, technicians will use an “amp clamp” or an inductive ammeter for electric forklift diagnostics. This device uses the electromagnetic field that forms when electricity flows through a conductor in order to determine how much current is flowing in a circuit.

Amp clamps have two significant advantages: firstly the circuit does not have to be opened up to install the ammeter, and secondly the amount of current flowing in the circuit cannot damage the meter. The disadvantage is that you must purchase an amp clamp that measures the range of current you expect to find. It is not possible to purchase a single clamp that will measure all current ranges.

With these basics, a good Multi-meter, and a wiring diagram or schematic the technician can navigate circuits to determine where voltages or currents exist in there correct specifications. Before replacing components a good mechanic will assure that all necessary wiring and circuitry is in place that could cause component to fail.

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Caterpillar Hydraulic Oil & Other Fluid Specs

Q: What lubricants do I use in my Caterpillar forklift?

A: It depends. Using the wrong lubricating fluids on your forklift can damage the truck and put the truck’s operator in danger. Check below for the correct forklift fluid specs for P3000 and P8000 models of Caterpillar trucks.

Cat forklift model P3000 P4000 P5000 P6000 P7000 fluid specs

•  gasoline engine = SAE5w-30; API classification SJ and abovemotor oil Intella Liftparts forklift fluid specs

 diesel engine = SAE5w-30; API classification CF and above

 transfer and differential oil = SAE80 (below 14°F) or SAE90 (14°F and above); API classification GL-4 or GL-5

•  powershift transmission oil = Dexron II

•  hydraulic oil = ISO VG32

•  brake oil = FMVSS No.116-DOT3 or DOT4 or SAE J1703

•  wheel bearing grease = NLGI No.2 grade multipurpose (lithium base); consistency of 265-295

•  chassis grease = NLGI No.1 grade multipurpose type (lithium base); consistency of 310-340

•  antifreeze = long life coolant (non-amine)

Cat forklift model P8000 P9000 P10000 P12000 fluid specs

•  gasoline engine = SAE5w-30, API classification SJ and above

•  diesel engine = SAE5w-30; API classification CF and above

•  transfer and differential oil = SAE80W (below 14°F) or SAE90 (14°F and above); API classification GL4 or GL5

•  powershift transmission oil = Dexron II

•  hydraulic oil = ISO VG32

•  wheel bearing grease = NLGI No.2 grade multipurpose (lithium base); consistency of 271

 chassis grease = NLGI No.1 grade multipurpose type (lithium base); consistency of 315


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Crown/Hamech forklift fluid specs

Q: What lubricants do I use in my Crown or Hamech forklift?

A: It depends. Using the wrong lubricating fluids on your forklift can damage the truck and put the truck’s operator in danger. Check below for the correct forklift fluid specs for various models of Crown and Hamech trucks.

MAX50 (gasoline/LPG engine): G15, G18, and G20(A)(S)HT-20

•  engine oil pan = engine oil (SAE 5w-30SJ)motor oil Intella Liftparts forklift fluid

•  TORQFLOW transmission case = DEXRON automatic transmission fluid

•  differential case = gear oil (SAE80W or 90W)

•  hydraulic tank = hydraulic oil ISO #32

•  brake reservoir = brake fluid (DOT 3) (SAE7OR-3)

•  greasing points = lithium grease (NLGI No. 2)

 cooling system = glycol-based coolant

MBX50 (gasoline/LPG engine): G20, G25, G28, G30, G32(S)(H)T-16, and G35AHT-16

•  engine oil pan = engine oil (SAE 5w-30SH)

 TORQFLOW transmission case = DEXRON automatic transmission fluid

•  differential case = gear oil (SAE80W or 90W)

 hydraulic tank = hydraulic oil ISO #32

 brake reservoir = brake fluid (DOT 3) (SAE7OR-3)

 greasing points = lithium grease (NLGI No. 2)

•  cooling system = non-amine long-life type

MBX50 (diesel engine): D20, D25, D28, D30, D32T-16, and D35AT-16

•  engine oil pan = engine oil (SAE 5w-30CH or SAE30W-30CH)

•  TORQFLOW transmission case = DEXRON automatic transmission fluid

 differential case = gear oil (SAE80W or 90W)

•  hydraulic tank = hydraulic oil ISO #32

•  brake reservoir = brake fluid (DOT 3) (SAE7OR-3)

 greasing points = lithium grease (NLGI No. 2)

 cooling system = non-amine long-life type

Post by Intella Parts Company, LLC