4000 Series Specs - Custom Hoists

To determine fluid displacement (in gallons) to fill a particular cylinder size, multiply desired cylinder stroke and “fill” factor from below chart. For fully extended displacement, multiply desired cylinder stroke and “extend” factor from below chart.

If you want to learn more, please visit our website EOOE.

Telescopic Fluid

Displacement Formula 

Example: 
Model No. 85--250 
Fill: .033 x 250 = 8.3 gal. 
Extend: .128 x 250 = 32.0 gal.

Note: Same formula used for single-acting and double-acting telescopic cylinders.

Extending Cylinder

To Extend: High pressure oil from the pump is directed by the control valve through port (A) 
to fill the cylinder. Any air in the hydraulic system will be trapped in the end of the cylinder (B) 
and may be bled off through the bleeder valve (C). It is advisable to bleed air from the cylinder 
on initial start up and on a weekly basis thereafter.

As the system pressure rises, the oil pushes on the bottom of the largest plunger (F) 
forcing it to move out. The outside diameter or sealing area of the plunger (D) 
determines the effective area.

As the plunger extends, the oil trapped between the plunger wall (E) is released through 
internal port holes in the plunger. When the largest stage is fully extended, the next largest 
will proceed to extend, etc.

To Retract: A single-acting telescopic cylinder must be retracted by gravity or 
mechanical means.

Normal Service Items 

Packing, wipers and bushings are considered normal service or replacement items. 
These items are subject to contamination from external and internal foreign materials, 
many of which are abrasive in nature, causing abnormal wear or damage to the parts, 
to the extent replacements are required.

Cylinders may be subject to leaking oil past the seal for various reasons requiring 
adjustment of the head/packing nuts. This is considered a normal installation and 
field service adjustment to correct the leakage.

Warning! 
Before making adjustments or repairs to the cylinder when mounted in the unit, 
use strong, heavy, positive supports to hold the body from accidentally lowering which 
can cause severe injury or death and/or damage to the unit and cylinder. Place control 
valve in the lower position to insure the pressure is relieved in the cylinder. High pressure 
can cause severe injury or death and/or damage to the unit and cylinder.

Procedure for adjusting headnuts on telescopic cylinders

A. For leaking cylinders

Want more information on Custom Hoist Cylinders? Feel free to contact us.

1. Loosen set screw(s) in headnut of leaking stage(s).
2. Tap headnut lightly around circumference with a hammer.
3. Using a chain wrench, back headnut off one half to one full turn. If plunger turns as you are turning the headnut, the plunger will have to be held, preferably with a strap wrench.
4. Cycle cylinder two or three times to reset vee ring packing.
5. Tighten headnut one half turn farther than it was loosened.
6. Tighten set screw(s).

B. For mis-sequencing cylinders:

1. Loosen set screw in headnut on stage that is sticking.
2. Tap headnut lightly around circumference with a hammer.
3. Using a chain wrench, back off headnut one half turn.
4. Cycle cylinder. If cylinder still mis-stages, turn headnut another half turn.
5. Cycle cylinder. If cylinder still mis-stages, tighten the headnut on the next stage that is extending. If plunger turns as you are turning the headnut, the plunger will have to be held, preferably with a strap wrench.
6. Tighten set screw(s).

C.  (a) Instructions for Self-Bleed Type Hydraulic Cylinders

After installation, cycle the cylinder approximately 5 times to remove air.  If erratic operation occurs, 
continue to cycle until cycle is smooth.  Cylinder will continue to bleed itself during use. 

Special considerations:
While the typical 5 cycles is usually sufficient; it may take several more cycles to bleed out enough air 
to eliminate erratic operation.  Not all systems are the same and considerably more cycles may be needed 
upon installation.

If air pressure is being used to aid in cylinder installation such as to raise mounting to attachment position, 
it is best to remove air pressure before cycling cylinder.

Older systems may be susceptible to air being induced; make certain that there is no part of the system 
that can allow air to be drawn into the system.

Avoid hose routing that will cause air to be trapped.  Large loops in the hose routing will be 
areas for air to collect.  Also, it may be more difficult to bleed if the reservoir is far from the cylinder and 
positioned very low with respect to the cylinder.

Always allow adequate air space in hydraulic reservoir per system recommendations.

Upon initial installation it may be necessary to allow time for the air to dissipate from the oil in the reservoir.
Check oil level periodically to avoid reservoir being drained during cylinder cycle.

C.  (b) Bleeding air from Single-Acting Telescopic Cylinders

1. Empty the dump body of any material.
2. Remove the cover plate from the doghouse of the dump body to access the cylinder bleeder valve.
3. Fully extend the cylinder, raising the empty dump bed.
4. Lower the dump bed to within one foot from the frame.
5. Turn the bleeder valve in a counterclockwise direction. This opens the valve and allows the air to escape from the cylinder.
6. When a steady stream of oil comes from the bleeder, turn the valve in a clockwise direction until it is closed.

NOTE: For consistent operation of telescopic cylinders, it is advisable to bleed the 
air from the cylinder weekly. 
If these procedures fail to correct the problem, contact the factory or an authorized 
service center for further instructions.

Safety Precautions 

WARNING! 
Rollover or lateral tilt can cause severe injury or death 
and/or damage to the unit and cylinder.

• The hydraulic cylinder will not prevent the dump body or trailer from rollover or lateral tilt. The cylinder is strictly a lifting device and is not a structural member of the unit. Cylinders are not to be used as a means of stabilizing the unit.
• The hydraulic cylinder mounted in the unit should be free to find its own trajectory line of extension, free of any lateral loading of the plungers. Misalignment of the top or bottom mountings, or mounting pins too tight, may cause scoring of the plungers, leaking, or improper sequencing which could cause the unit to upset.
• The hydraulic cylinder will not withstand lateral pressure when the unit is leaning. Only activate the cylinder when the tractor and trailer are in a straight line (not jack-knifed). Do not activate the cylinder while on unlevel or soft ground, or during heavy crosswinds. Doing so may cause the unit to upset.
• Do not activate the cylinder while personnel or equipment are alongside or behind the dump body or trailer.
• The operator should stay at the controls during the entire dumping operation. If the body starts to lean, the operator should immediately lower the dump body or trailer. It is important to slowly position the cylinder control valve into the hold position to avoid subjecting the cylinder to high pressure.
• Do not overload the unit. The load must be distributed evenly during loading or unloading to avoid rollover and lateral tilt. Loads stuck while the cylinder is partially or completely extended increases the hazard of rollover and lateral tilt. Lower the dump body or trailer entirely with the cylinder control valve partially open (avoid lowering the dump body or trailer with the cylinder control valve completely open). Then unload the dump body or trailer manually or with an alternative mechanical aid.

WARNING!
Shock pressure can cause severe injury or death 
and/or damage to the unit and cylinder.

• Do not use the cylinder to loosen loads stuck in the dump body or trailer. Lower the dump body or trailer entirely with the cylinder control valve partially open (avoid lowering the dump body or trailer with the cylinder control valve completely open). Then unload the dump body or trailer manually or with an alternative mechanical aid.
• Do not move the truck and jam the brakes while the cylinder is partially or fully extended to loosen loads stuck in the dump body or trailer. Lower the dump body or trailer entirely with the cylinder control valve partially open (avoid lowering the dump body or trailer with the cylinder control valve completely open). Then unload the dump body or trailer manually or with an alternative mechanical aid.
• Do not move the truck until the dump body or trailer is lowered completely.

WARNING!
Over pressurizing the cylinder can cause severe injury or death 
and/or damage to the unit and cylinder.

• Do not operate the cylinder at pressures greater than P.S.I. unless otherwise approved in writing by Custom Hoists, Inc.

WARNING!
Worn or damaged hydraulic hoses can cause severe injury or death 
and/or damage to the unit and cylinder.

If you are looking for more details, kindly visit dual hydraulic cylinder.

• Hydraulic hoses should be checked regularly and replaced if worn out or damaged.

We've got a little design task here. After looking at the options and the constraints involved with a module that installs in another machine, we're thinking about designing our own custom hydraulic cylinders--roughly 2.5" diameter, but with a short stroke, only about 1/4". The standard off-the-shelf Parker compact hydraulic cylinders won't integrate cleanly. Even though it's a pain, it looks like things will package best if we machine the bores right into some other components.

We've made plenty of custom pneumatic cylinders but never hydraulics. Searching online, I can't find much info for hydraulic cylinder design guidelines. If we're operating at psi, is there any magic involved with seal selection beyond the Parker o-ring/seal handbooks? It's going to see a lot of cycles, about 5 million per year, so longevity is a concern, too. It's ok if the customer has to spend 2 hours changing seals every million cycles, but the metal needs to last a lot longer. Can we do this in polished steel bores, or do we need to get everything hard-coated?

It'd be great to get some input/advice from someone who's been here before.

When you say " won't integrate cleanly. " is it length, diameter, mounting, other?

There are many types beyond Parker tierod style.

What makes your application unique?

Ed.

We're trying to pack 10# of shit in a 5# bag. That's the basic problem; haven't found any OTS cylinders that pack as tight as we need. On the other hand, the models show that everything would fit pretty well if we machine the cylinders directly into some other parts of the system.

One of the rules of brainstorming is that there is no bad idea, because it might stimulate a better idea.

On that note, you can buy honed tubing, by the foot:
Honed Tubing Supplier | Pre Honed Steel Tubing | Hydraulic Cylinder Tube Distributor

Maybe you could buy a standard cylinder, keep some of the components, glands, rod ends, etc, then incorporate this into your existing components.

Can't really visualize what you are trying to do.
Bob

I like the idea of parting out somebody else's piston-rod-seal assembly and installing it in our custom cylinder. Thanks.

We've got a little design task here. After looking at the options and the constraints involved with a module that installs in another machine, we're thinking about designing our own custom hydraulic cylinders--roughly 2.5" diameter, but with a short stroke, only about 1/4". The standard off-the-shelf Parker compact hydraulic cylinders won't integrate cleanly. Even though it's a pain, it looks like things will package best if we machine the bores right into some other components.

We've made plenty of custom pneumatic cylinders but never hydraulics. Searching online, I can't find much info for hydraulic cylinder design guidelines. If we're operating at psi, is there any magic involved with seal selection beyond the Parker o-ring/seal handbooks? It's going to see a lot of cycles, about 5 million per year, so longevity is a concern, too. It's ok if the customer has to spend 2 hours changing seals every million cycles, but the metal needs to last a lot longer. Can we do this in polished steel bores, or do we need to get everything hard-coated?

It'd be great to get some input/advice from someone who's been here before.

I build and modify hyd cylinders on a daily basis. I can help you with your design for you to build or I can build it for you.
If you can shoot me a I can give you my number. way to many questions and parameters to answer on here
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