FAQs

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  1. What are the advantages of slipforming curb over hand forming?
  2. Why does my front crawler search back and forth when I’m pouring?
  3. What is the recommended maintenance schedule?
  4. What are some of the Brand Name Equivalents for the hydraulic oil?
  5. Why does the post leak down when the engine isn’t running?
  6. Why does my Change Filter light come on but then go off when my machine warms up?
  7. Why does my post or front crawler drift when the amplifier is in Standby?
  8. For slip-form curb or barrier wall, what mix design or slump do you recommend?
  9. For extruded curb, what mix design or slump do you recommend?
  10. How do I order molds?
  11. If I am hand forming, what is the break-even point on purchasing a curb machine?
  12. Can I bypass the emergency stop?
  13. Troubleshooting the High Pressure Water Pump
  14. What can I expect in the way of profit, per day, with a curb machine?
1) What are the advantages of slipforming curb over hand forming?
  • Slipformed curb is stronger: Low-slump concrete is stronger than the high-slump concrete used in hand pouring.
  • Slipformed curb is faster: You get more production with the same number or fewer people, resulting in lower price to the end user.
  • Traffic patterns are diverted for a shorter time due to the speed of completing the project; thus, the traveling public (the taxpayer) is happier.
  • Low-slump, air-entrained concrete is more resistant to salt and slag deterioration.
2) Why does my front crawler search back and forth when I’m pouring?

Several things may cause this. Here are a few simple procedures to help determine where the problem is originating. Do the following one at a time to determine the problem.

Do this: To determine if the problem is this:
Swap your steering sensor with a sensor you know is good. Defective Sensor
Swap the steering sensor curly cord with a cord you know is good. Defective Curly Cord
Swap the steering amplifier with an amplifier you know is good. Defective Amplifier
Swap the servovalve with one you know is good (steering servovalves on late model 5700s, 8700s, and 5700-Bs are different from the grade and slope servovalves). Defective Servovalve
Check the feedback pot for proper operation and correct timing. Defective or Improperly Timed Feedback Pot

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3) What is the recommended maintenance schedule?
Check and Clean Schedule Interval
Ref. No. Identification Type of Service Daily (10 Hrs.) Weekly (50 Hrs.) Monthly (250 Hrs.)
1 Engine Oil Level Check X - -
2 Engine Coolant Level Check X - -
3 Radiator / Cooler Check X - -
- Radiator / Cooler Clean - - X
4 Engine Air Filter Check X - -
- Engine Air Filter Clean - X -
5 Hydraulic Oil Level Check X - -
6 Hydraulic Oil Cooler Fins Check X - -
7 Fuel Level Check X - -
8 Conveyor Clean X - -
9 Conveyor Torque Hub Oil Level Check - - X
10 Crawler Chain Tension Check - X -
11 Crawler Torque Hub Oil Level Check - - X
12 Crawler Idler & Roller Bearings Check - - X
13 Trimmer Torque Hub Oil Level Check - - X
14 Pump Drive Oil Level Check - - X
15 Mold & Hopper Clean X - -
17 Sensor Hubs & Wands Clean X - -

 

Change Schedule Interval
Ref. No. Identification Type of Service 50 Hrs. 250 Hrs. 500 Hrs. 2000 Hrs.
1 Charge Filter Change 1st Time X - -
2 Servo System Hydraulic Filter Element Change 1st Time X - -
3 Hydraulic Tank Return Filter Element Change 1st Time X - -
4 Hydraulic Tank Breather Filter Element Change - X - -
5 Engine Oil Change 1st Time X - -
6 Engine Oil Filter Change 1st Time X - -
7 Engine Coolant Change - - - X or 2 years
8 Air-Cleaner Element Change - X - -
9 Fuel Filters Change 1st Time - X -
10 Hydraulic Oil Change - - - X
11 Hydraulic Tank Suction Screen Filters Clean - - - X
12 Crawler Torque Hub Oil Change - - - X
13 Trimmer Torque Hub Oil Change - - - X
14 Pump Drive Oil Change - - - X
15 Conveyor Torque Hub Oil Change - - - X

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4) What are some of the Brand Name Equivalents for the hydraulic oil?
Hydraulic Oil Brand Name Equivalents
AMERICAN Industrial Oil 46
CITGO Pacemaker 46
EXXON Nuto H46 & Terrestric 46
MOBIL DTE 25
PHILLIPS Mangus 46
SHELL Tellus 46
SUN Sunvis 46
TEXACO Rando 46
UNION Unax 46

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5) Why does the post leak down when the engine isn’t running?
There are 2 possible reasons for this occurrence:
Probable Cause: Action:
Defective counter balance valve Exchange the counter balance valve on the trouble post with a known good, pre-set valve.
• If the post stops leaking down, replace the defective counter balance valve.
• If the post contnues to leak, continue troubleshooting.
Excessively worn post cylinder Visually check for hydraulic oil leakage at the rod end of the cylinder (oil will seep around the lower cylinder mount bolts on the underside of the inner post yoke, if there is external leakage).
• If excessive external leakage is present, repair or replace hydraulic cylinder.
• If no excessive leakage is present, the problem could be internal leakage. Remove the cylinder and disassemble, inspecting the cylinder bore and piston o-rings.

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 6) Why does my Change Filter light come on but then go off when my machine warms up?
Probable Cause Action
Cold Hydraulic Oil Warm up the machine to operating temperature before using.

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7) Why does my post or front crawler drift when the amplifier is in Standby?
Probable Cause: Action:
Servovalve NULL position Adjust the NULL position on the servovalve (as discussed in Section 4, Page 4-15 of the 5700-B Maintenance Manual Revision 12-15-96) until the drifting stops. If drifting cannot be adjusted, replace or rebuild the defective servovalve.

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8) For slip-form curb or barrier wall, what mix design or slump do you recommend?
For a typical curb:
Contents Cubic Yard Cubic Meter
Sand 1500# 891 kg
Cement 540# 321 kg
Coarse Aggregate 1600# (1/2″) 951 kg (13mm)
Water 39 gallons (320#) 193 liters
Air 4% – 6% 4% – 6%
1 1/2″ – 2″ Slump,  3000 psi
For a typical barrier/parapet:
Contents Cubic Yard Cubic Meter
Sand 1400# 832 kg
Cement 700# 416 kg
Coarse Aggregate 1700# (3/4 to 1″) 1011 kg (19 to 25mm)
Water 32 gallons (262#) 158 liters
Air 4% – 6% 4% – 6%
1″ Slump,  4000 psi

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9) For extruded curb, what mix design or slump do you recommend?
Concrete Mix Design(for a cubic yard of concrete):  Very low slump – zero or close to it.
> 1,950 lbs of sand, SSD 4% moisture
> 517 lbs (5 1/2 sacks) of cement
> 1,442 lbs of 3/8″ gravel or crushed stone
> 16 gallons of water
> 3% to 5% air

 

Use this as a guide and make minor changes as required to result in the desired product.

 

Asphalt Mix Design:
> Virgin mix is recommended.  The aggregate should be clean and dry.
> Liquid asphalt content by weight for virgin mix should be 8%.
> The working temperature should be in 200-285 degree (F) range.
> If the mix is too hot, the curb will crumble.  If the mix is too cold, the machine won’t handle properly.
> The mix should contain a mixture of both large and small aggregates and avoid rounded or smooth aggregate.
10) How do I order molds?
Click here to order molds.
11) If I am hand forming, what is the break-even point on purchasing a curb machine?

If you can pour as much as 20,000 to 25,000 linear feet (6,000 to 7,500 m) of curb per year, you can justify the cost of a new or used Power Curber, financing it over a 3 to 5 year period.  To pay for the machine, you build $1 a foot into the curb cost.  The machine will increase your production, cut your labor, and allow you to bid more competitively.

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12) Can I bypass the emergency stop?

Never bypass or disconnect the machine’s Emergency Stop Circuit in ANY manner which will render it inoperative.

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13) Troubleshooting the High Pressure Water Pump
Problem Cause Remedy
Pulsation Valve stuck open. Check all valves, remove foreign matter.
Low pressure Worn nozzle. Replace nozzle, use proper size.
Air leak in inlet plumbing. Disassemble, reseal and reassemble.
Relief valve stuck, partially plugged or improperly valve seat worn. Clean, adjust relief valve; check for worn and dirty valve seats. Kit available.
Inlet suction strainer clogged or improperly sized. Clean; use adequate size. Check more frequently.
Worn packing. Abrasives in pumped fluid or severe cavitation. Inadequate water. Install proper filter. Suction at inlet manifold must be limited to lifting less than 20 feet of water or -8.5 PSI vacuum.
Fouled or dirty inlet or discharge valve. Clean inlet and discharge valve assemblies.
Worn inlet, discharge valve blocked or dirty. Replace worn valves, valve seats and/or discharge hose.
Leaky discharge hose. Replace hose.
Pump runs extremely rough, pressure very low Inlet restrictions and/or air leaks. Stuck inlet or discharge valve. Replace worn cup(s), clean out foreign material, replace worn valves.
Restricted inlet or air entering the inlet plumbing. Proper size inlet plumbing, check for air tight seal.
Water leakage from under manifold. Slight leakage Worn packing. Install new packing.
Cracked plunger. Replace plunger(s)
Oil leak between crankcase and pumping section. Worn crankcase piston rod seals. O-Rings plunger retainer worn. Replace crankcase piston rod seals. Replace O-Rings
Oil leaking in the area of the crankshaft Worn crankshaft seal or improperly install oil seal O-Ring. Remove oil seal retainer and replace damaged O-Ring and/or seals.
Bad bearing. Replace bearing and any spacer or cover damaged or cover damaged by heat.
Water in the crankcase May be caused by humid air condensing into water inside the crankcase. Change oil intervals. Use SAE 30 non-detergent oil.
Worn packing and/or piston rod sleeve, O-Rings on plunger retainer worn. Replace packing. Replace O-Rings.
Cracked plunger. Replace plunger(s)
Oil leaking from underside of crankcase Worn crankcase piston rod seals. Replace seals
Scored piston rod. Replace piston rod.
Oil leaking at the rear portion of the crankcase Damaged crankcase, rear cover O-Ring, drain plug O-Ring, or sight glass O-Ring. Replace cover O-Ring, drain plug O-Ring, or sight glass O-Ring.
Loud knocking noise in the pump. Pulley loose on the crankshaft. Check key and tighten setscrew.
Broken or worn bearing or rod(s). Replace bearing or rod(s).
Valve stuck open or shut, or not opening enough. Replace bad valve.
Frequent or premature failure of packing. Scored, damaged or worn plunger. Replace plungers.
Over-Pressure to inlet manifold. Reduce inlet pressure.
Abrasive material in the fluid being pumped. Install proper filtration on pump inlet plumbing.
Excessive pressure and/or temperature of fluid being pumped. Check pressures and fluid inlet temperature, be sure they are within specified range.
Over-pressure of pump. Reduce pressure.
Running the pump dry. Do not run the pump without water.
Upstream chemical injection. Use downstream chemical injection.

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14) What can I expect in the way of profit, per day, with a curb machine?

Realizing that costs may vary, depending on your location, here is an estimate on 24-inch wide curb and gutter, for your comparison:

Concrete:
$120/yd divided by 20 ft. yield per yd = $6 per linear foot

Labor:
5 men x$30/hr x 8 hours = $1,200
$1,200 divided by 2,000 linear feet per day = $.60/foot

Total Cost:
Direct cost (concrete + labor) = $6.60/foot
Overhead (estimate) = $1.65/linear foot
Total cost (estimate) = $8.25/linear foot

Daily Profit:
Bid price = $12/foot = $24,000
Less cost: $8.25 x 2,000 = $16,500
Daily profit (estimate) = $7,500

For your specific circumstances, you can edit these formulas with your price for concrete, the number of men in your crew, and your hourly rate.  For this example, we’ve used 2,000 linear feet per day which is a good average.  Depending on the type of job you’re on, how well the job-site is prepared, how quickly your concrete supply is delivered, and other factors, your production rate may vary.  For this example, we’ve used 25% of the direct costs (concrete and labor) as the estimated overhead.  You can edit these entries as well based on your specific situation.

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