Oilgear PVWH34 Pump Repair – Skidder Pumps

16th August 2010 by Doug Hanson 1 Comment

How To Build A Bullet-Proof Oilgear PVWH34. Written for Hanson Hydraulics Ltd. Blog: This is a reposting of the original aricle I had written for the first Hanson Hydraulics Blog. I get a lot of requests for it, so here it is reposted. I will add some pictures to it in the future, but in the meantime, here is the text: 

This repair applies to other models of the PVW* ** family of course, but this case pertains specifically to the Oilgear pumps used in John Deere and Timberjack skidders.  This is kind of a special case because there are a couple of “bizarre” steps that wouldn’t normally be done.

Continue reading…

Sphere: Related Content

Hydraulic Transmission Case Flushing

24th May 2010 by Doug Hanson No Comments

Hydraulic Transmission Case Flushing

Dynapower pump

Modified pump for case flushing

Case flushing in hydrostatic transmissions is almost essential in extending the life of the transmission. Flushing will substantially reduce pump and motor operating temperatures. The arrangement depends on whether the Hot Oil Shuttle is integral to the motor or is an external block. If it is integral to the motor, the case drain line from the top of the motor should run over to the bottom case drain port on the pump. The upper case drain port on the pump should then run through a cooler or heat exchanger if equipped. Depending on the make of pump, it may be possible to run the case drain line through a designated case return filter, however with some shaft seal arrangements, the seal will not tolerate the back pressure created from pushing oil through the filter, especially cold oil. Please keep in mind that any back pressure in the pumps case drain line will now be additive to the back pressure on the motors case drain line.

If the Hot Oil Shuttle is external to the motor, plumb the relief flow from the Hot Oil Shuttle to the bottom case drain port on the motor, then continue as stated above. The draw back to such an arrangement is that contamination created by the drive motor may end up contaminating the case of the pump, however if that is the case, chances are you already have damage within the pump as well.

This arrangement makes a huge difference on Low Speed High Torque motors that have extremely low case drain flow rates. With these motors, the stagnant case drain oil sits in the case, becomes extremely hot, and looses viscosity and lubricating properties. In a Staffa or KYB motor, the bronze surfacing of the connecting rod then smears on the crank shaft, as well as the connecting rod ball-end and piston gall up. Life on these motors is extended greatly by case flushing.

Caveat – do not exceed maximum recommended case pressures!

Older designs such as Dynapower units had charge pumps that did not relieve into the case of the pump; instead they discharged their charge pump flow across to the suction side of the charge pump. These charge pumps can be modified to discharge relief oil externally, which can then be plumbed into one of the ports in the trunion caps. This makes a huge difference on mobile equipment such as pavers or rollers that spend a lot of time idle over hot tarmac. A picture of such an arrangement is shown here. If you have any interest in this particular modification, please email me and I will provide more details.

Sphere: Related Content

Eaton VIS motors – Drifting Grapple Rotate Motors

23rd May 2010 by Doug Hanson No Comments

Eaton VIS 45 motors are commonly used in grapple rotate applications, however they are the open loop version of the motor which allows drifting in neutral do to the method used to lubricate the bearings and drive spline in the motor. This motor can be arranged as a closed loop motor which will provide proper lubriction and better load holding capability if plumbed correctly.  The complete write up is in this PDF file: Closed_Vs_Open_VIS

Here is an extract:

The Eaton VIS motor is commonly used in grapple rotate applications. The open loop version of the VIS in this application allows rotation drift do to the method used in providing lubrication oil for the inboard shaft bearing and drive splines. The method of lubrication relies on two check valves that seat inside of the valve star.  The port with the highest pressure provides the lubrication for the inboard bearing. The highest pressure unseats it’s ball in the star, and feeds the lubrication passage. The other check valve prevents flow from bypassing through both check valves.

There are two drawbacks to using the highest pressure port to provide the lubrication for the bearing: 1) the high pressure drop creates heat, and 2) When the control valve (in it’s neutral position) is used to hold a load, this load induced pressure is allowed to flow through the check, allowing the load to rotate.

 These motors can be converted to closed loop operation which will reduce the amount of drift experienced. At this time this idea is  theoretical and has not been tried in this application. Modifications of an OEM system may void warranties and must be done at the users own risk.Closed_Vs_Open_VIS

Sphere: Related Content

Check out Insane Hydraulics

23rd May 2010 by Doug Hanson No Comments

Here is another great site to check out. Full of humor and good information. Be sure to take the “Simple Test”.  With so few hydraulic related sites giving out detailed component information, this site is a must to check out.

Sergiy Sydorenko’s Insane Hydraulics:

http://www.insanehydraulics.com

Sphere: Related Content

Difficult to repair hydraulic cylinder

26th April 2010 by Doug Hanson No Comments

Written for Hanson Hydraulics Ltd. Blog: Here is a not so easy “quick reseal only” hydraulic cylinder repair.  First step was using an industrial sized face spanner with 12′ of pipe, didn’t budge. Heated the barrel up around the gland, didn’t budge.

Next step, build a socket to fit the hydraulic wrench. Started with two sector rings. Used the holes in the sector rings as a jig to drill and tap the face of the gland. Continue reading…

Sphere: Related Content

Excavator Hydraulic Cylinder Seals and Inspection

1st April 2010 by Doug Hanson 2 Comments

Hanson Hydraulics Ltd. Blog article:

Start inspection with the rod.  Measure the cylinder rod diameter with a micrometer, checking over the entire length and at various spots around  the diameter. You’re looking for low spots. A low spot that you can’t see may exist from previous rod repairs.  Check the rod for pits, dents, dings, or scratches, if they are present, the rod will need repairing or re-chroming. Excavator cylinder rods are often nickel plated, then chrome plated over nickel. If the rod requires re-chroming it is stripped in a strip tank, however the nickel will not strip of electrically, so it must be mechanically removed.  You don’t need to worry about this as the rod will have to go out to a chrome shop. I’ll save the chroming info for another posting. Continue reading…

Sphere: Related Content

Excavator Hydraulic Cylinder Repair

15th March 2010 by Doug Hanson 1 Comment

Dissmantling and repairing  a Hitachi EX150 Bucket cylinder.

Hanson Hydraulics Ltd. Blog article:

Remove the flow tubes, grease fittings and pin wipers from the eyes

Strap the barrel down and put a bar through the barrel eye to prevent the barrel from turning. Match mark the gland to the barrel as the port in the gland must return to its position when reassembled in order for the flow tubes to line up again. 

01

 

Remove the eight socket head cap screws that hold the gland to the barrel. If you forgot to mark the gland have a look at the face of the barrel, there may be a blind hole that is not used, and this hole should have left a mark on the face of the gland.  Mark accordingly as after the parts are cleaned up for reassembly, you may not be able to see the mark any more.

Continue reading…

Sphere: Related Content

Waratah Poclain motor reseal MS08

11th November 2009 by Doug Hanson No Comments

To perform a fast shaft seal replacement on a Poclain MS08/Waratah motor:

Hanson Hydraulics Ltd. Blog article:

A quick reseal on a Poclain MS08-9-12A-A08-1129-DJMO motor. This unit is off of a 622B Waratah processor head. A factory seal kit is around $900.00. In this instance the customer wanted just the shaft seal replaced with absolute minimum down-time.

Ordering the high pressure double lipped shaft seal and housing orings came to $30.00. The following description of work covers only a fast shaft seal replacement. This is not a complete rebuild.

IMG00252aFirst, note direction of feed wheel. To change the direction, the wheel flips over, allowing the motor and wheel assembly to be used on the other arm. Remove the wheel.

Remove the housing bolts, remove the port end cover, be careful as the distributor may drop out of the cover, usually they stay sitting on the cylinder block, but be careful not to drop it, there are springs that load the distributor up against the cylinder block. Continue reading…

Sphere: Related Content

Spool Valve Spring Compressing Tool

8th October 2009 by Doug Hanson No Comments

 

Here is a little tool that comes in handy when working on spool valves that use snap rings to retain the springs to the spool, for example a Parker VDP12.

Brand new 2078

Brand new 2078

In order to compress the spring to easily remove the snap ring, a modified KD Tools Model# 2078 “Overhead Valve Spring Compressor” can be used effectively.

 

 

 

 

Continue reading…

Sphere: Related Content

Pattern Changer Valve – Holmbury Inc.

23rd September 2009 by Doug Hanson No Comments

Holmbury’s OCUKAC2318 is a high quality  pattern changing valve with a steel body and hardened spool for pilot applications, such as switching between John Deere and Cat control patterns on excavators.

Hanson Hydraulics Ltd. Blog article:

Pattern Changer Valve
Pattern Changer Valve

I recently installed one of these valves on a Caterpillar 321B excavator. Right out of the box, its ready to go. On this installation however, I decided to modify the spool and make a spool extension, so the handle would come up through the 1/2″ floor plate. This allowed utilizing all of the existing pilot lines without modification, and the addition of four 3′ pilot lines. Continue reading…

Sphere: Related Content

Bad Behavior has blocked 3 access attempts in the last 7 days.